oh pfffffffft yes, size matters...
If your so small you can't scratch ma hole, then I'm sorry but I won't be very satisfied..
but that's about where it stops, as long as you can reach most of the spots in my arse I'm pretty happy.
Having said that, I've this little button, if you start smacking that thing just right, I'll cum so gawd damn hard that my entire body will just tense up (inside and out) and I'll get the roof sticky.
Thankfully I don't need nor desire that little button to be pushed by guys every time, yes it's an intense feeling, but I never tell anyone where it is anyway (not giving away all ma secrets) and it's a little outta reach for the average endowment, but I enjoy sex immensely with any man I'm with and I don't want that spot hit all the time, it would totally kill it for me.
For those who can reach beyond it, every time they slide past it, I get a little tingle that goes from my arse to my crotch to my tummy and then goes up my back, but doesn't make me cum thankfully.
So yes, size is important to me, to a certain extent if I am bottoming for him, but only so far as he can reach my prostate and give it a good thumping, anything beyond that to that other spot is just spare change..