Pass the sign up sheet, I want to help. (and sorry about the spelling, having a bad dys day).
But honestly, I'd be cheating a bit. See, I've DONE this research already. And I'm not just spouting platitudes; it really, truly isn't a big damned deal.
I know, I know. Just troll through the comments on guy's pics here, and you'll find women passing compliments about men who have more than the average gift. I'm sure I've done it. But I know for a fact that I've also gone a little swoony at a guy who posted ages ago, not because of the size of his dick (which was pretty average as I remember it) but because it really did have a lovely curve to it. Nothing to do with size. And I think that's one of the things you have to remember when you're looking at pro-sizish comments, or hearing them in movies, or what have you. It is entirely possible that people might be complimenting form. And
Truthfully, cocks have got that much in common with breasts. The aesthetic standards imposed on them have little to do with their function. Babies don't get more milk from big breasts. And despite the press, large cocks don't give better lays. But both organs have become symbols of sexuality, and all the way back to prehistoric art the symbol of sexuality is exagerated to draw attention to it. This is best demonstrated by the exception, some archaic statues of fertility goddesses emphasize the stomach or vulva (and those can look downright scary to modern, western eyes) rather than the breasts. In our culture, it's most often dicks and breasts.
But does that make it real? Obviously not in the case of breasts, but there I have to say that breasts have a better PR officer. It's clear that's purely aesthetic. Women have spent a lot of energy teaching each other that we are each of us attractive in our own way (nonetheless breast augmentations are still one of the most commonly undergone proceedures). Guys, probably because it's not something that gets judged in the first glance, haven't had that education. For a lot of you, I imagine you watch Sex in the City, and feel like you're finally getting the real story. Size DOES matter, Kim Cattrell said so.
Or at least her speach writer did. Who may not know what they're talking about.
The woman on the corner, talking to her girlfriends, bragging about the huge dick she screwed that weekend? Noise. She's part of the same societal matrix...she's heard it her whole life. Hung like a horse = good. She's bragging in shorthand, everyone does. You can't take talk like that for data, it's too embedded in the culture.
The real question you ask, Bel, is does it make a difference in bed. Really and truly. In a blind fuck test, would women go for the bigger cock even most of the time. I know I wouldn't. And I had the worst possible history.
Poor innocent little Ginger's first experience was with a guy whom society would call blessed. Having only really had experience with tampons up till that point, never having owned a vibrator much larger than my thumb, and not being the dirty pic coneseur I am today....I honestly gaped. That was in no way gonna fit. But it did, and it was wonderful. And I didn't know ALL guys didn't come that shape. Learned different while we were together (he was an education in many ways), and decided I was a lucky girl.
My next experience was the other end of the scale. Slightly smaller than what I have since learned to be average. Was I disappointed when I got the wrapping off? Yeah. Why? Because I'm an American girl. I was taught to believe that the reason my first was so damned good was because he was so damned big. "Ah well," says Ginger, "better than nothing." Did it feel different? Yes. Why? Cause guys feel different. They screw differently. I don't know why. Did I feel less filled, shockingly no. Was the sex less good, not really. Less practiced, therefore less effective, but not because I was feeling a lack of something. And we eventually got JUST as good.
It turns out that the "tight pussy" is another damned myth. The vagina is like a sock. It starts out collapsed and stretches to accomidate what's put in it. Girls are tighter on their first time, in part because we're TENSE as hell and tend not to be as well lubricated. Everything else you feel is muscle control. Babies don't stretch us out, but they can damage the muscles (from what I understand), which then have to be rebuilt. But women really are one size fits all, and we're wrapped just as tightly around anything you put in us. We're terribly accomidating creatures, biologically. The word tight gets used in erotic writing because it's evocative as hell, the idea of something tight around your dick is going to turn you on. Honest to god, if it weren't true....tampons would come in sizes to fit (not just different absorbancy). They'd HAVE to.
Can we have great sex with big cocks? Yup. Why? Cause some of us like penetration. ANY penetration. Can we occasionally have mind blowing sex with big cocks? Sure. Can some women prefer sex with men who have a salami in their shorts? Yeah. Some can. But I think it's for the same reason some women like leather. It's a kink. It's a mind game. It's a result of what they heard and saw and felt growing up as their sexual identity developed. They SEE a big cock and get aroused, the degree of arousal determines the intensity of their orgasm. NOT the cock itself.
But, back to the sexual adventures of yours truly. The guy I'm with now, whom I love and with whom I've had the best sex of my life, isn't all that "well endowed". I slept with him before I was emotionally committed, I could've easily jumped ship and looked elsewhere. But he's better than anyone I've ever been with, because he knows how to make love to me. Maybe he wouldn't be as good with the girl downstairs...at least until they've gotten to know each other's twists. But honestly, our first time was better than my first time with my largest lay. The ONLY point I regret was when the idiot appologised for his "lack of size," for which I had to hit him with a pillow and punish him with a blow job. BTW, he fits PERFECTLY in my mouth and just up against the back of my throat...and I knew he would the first time I saw him. THAT turned me on, welcome to one of my personal kinks

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I have never yet laughed when a man dropped his drawers unless he's drawn a smily on the head of his cock. I've never yet kicked a man out of my bed for not living up to a standard. And while I have ONCE not realized that penetration had begun (because 2 hours of intermittent oral and vibration will eventually NUMB you), I sure as hell did before he had finished his first stroke...and he wasn't one of nature's wonder's either. I have never ever felt "nothing", and I think women who say that are purely being hurtful. And gf gossip is dictated as much by society, what we think will impress our friends, more than anything else. That said, it's something I DON'T talk about with folks who know my guys...I'm even a little uncomfortable talking about it here...and that's saying something, as comfortable as this place is. I never bragged about my first to my friends. I don't want it to sound like I'm bragging here.
So does it make a physical difference? Biology tells me no. Personal experience tells me no. Television/old wives tales tell me something else....answer, turn off the damned television and have sex

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Anyway, you're right, Bel, that society gives mixed messages. And I understand the temptation to assume that the way to resolve the conflict is to guess that women are trying to protect male egos by lying to them. Hell, I have lovely curving hips...but it took me ages to believe that they weren't horribly ugly because they weren't supermodel slender. I just assumed people were lying to me to make me feel better or get me into bed. But I honestly don't know what I can say to convince you, or any other guy, beyond what I already have. If you blindfolded me, tied me down, and had a parade of dicks come screw me (and, by the way, yes PLEASE)...I really don't believe I could pick out which was which unless one was so big it HURT (and it can if it jabs your cervix)...which really isn't something one wants to be remembered for.
More than my 2cents...anyone have change for a $20?
G