So I've been follow the "does size matter" debate pretty closely and found some threads here. I've got my own point of view on this since I'm about average size, but damn awesome in bed regardless. Aside from my first two lays the girls have always came from intercourse. Now that being said, my wife comes just fine, but when we messed around with toys I found out first hand how much size still matters.
I surprised her with a 10x7 dong one night after we talked about trying new things in bed. She wasn't able to accomodate it at first due to the thickness, but once we got past that after about all of, oh...2 minutes or so, she was taking 7 or 8 inches no problem. Any more and it would hurt her though. So long as I stopped at that depth and went crazy on the speed she'd orgasm faster and stronger than she ever did with plain old me.
Anyway, I remember it like it was yesterday though when something different happened. I was using the big dong on her and she started to ograsm, but she was really violently cuming and started moving around and bucking her hips. When she did she sort of sucked in the last couple inches and was actually balls deep on the dong. I think I was hitting her epicenter and she had the loudest hardest orgasm of her life. So we talked about it later and I tried looking it up online what just happened. That's actually how I found this site. A few days of googleing and I couldn't really come up with anything besides the epicenter explaination.
Since we were curious I went out and got a bigger dong, I think it was modeled after a porn star, but I forget the name. This new one is 7.5" around and 12" long. The first couple times we used it it was the same as before being limited to about 7-8" inside her, but about 2 or 3 weeks later when she was really into it she arched her back the same way as before and the sucking thing happened again. Sure enough she took it balls deep. Not sure where it's all going since she's only 5'3" and 130lbs.
Anyway, my point is that while I can get her off just fine, depsite her small stature she can take that HUGE dong to the hilt when I hit the right spots with it. AND IT'S A MUCH MORE POWERFUL ORGASM. So IMO size matters with her. I'm not worried about it though since I'm still the best in bed for almost all the women I've ever been with, and I can't change my size so I don't worry about it. Worst case if she really wants a big boy we have the toys we can break out. Plus I think I'm way better with the toys then a guy could ever be in terms of speed, depth control, and going as long as needed without ever having to worry about blowing a load.
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On the flip side of the coin....
I nailed this redhead years ago. She was so tight I couldn't even get it all in with her and we fucked like crazy for a couple weeks until she moved back to her country--she was only here for a college class over the summer. Despite my average size she was just small down there and that was that, so even small guys would be plenty big enough for her.
This is what makes me think the size issue is really a moot thing. If a guy isn't big enough for his girl then by the same token she's too big for him. In other words they're not a good match and they'd be better of with someone who is. My wife can take a big one, but since I get her off just fine we still match. Sure, a bigger guy would probably be a better match from a guy's perspective due to what she's capable of fitting down there, but since we don't have problems we're happy. And if she does't mind being sore afterwards we can go the extra distance with the dongs and give her that extra special orgasm.