Hmm. I use to think about this because of conversations I overheard from other men. Conversations I've heard from women are usually quite different with really big ones being something of a curiosity or something to giggle about but not being taken as seriously as the men seemed to.
From personal, anecdotal experience, most women seem to get their freak on just fine with smaller units after having the big one.
I will say there seems to be a percentage of women who prefer the big one but there are also a percentage of women who like it to be smaller than average.
The largest percentage seem very good with average or just above but not really big or small.
To be fair, my measurements are apparently above the large end of average but I'm not huge and I know for a fact I have had lovers who were with really big men before me but absolutely lost their minds with me in bed.
Mrs. Conan's first husband was anomalous in the unit department, sporting a log compared to my bat and she can't get enough of me while she actually didn't enjoy sex that much with him. She actually didn't ever see what people liked so much about sex before meeting me. She liked it ok but didn't get what the big deal about it was until she was with me for a while and really started liking it.
I won't say size is totally unimportant but there are many, very important factors for sex to be good and as long as your unit isn't really small, the majority of women will have a good time with it.
Mrs. C still has to be worked up and very aroused to accept me even though she use to have something much bigger working her box.
She responds with high levels of satisfaction and I still have to be careful until she is really stretched and ready before we start moving with vigor. Once we are really into it, I can tell that she could be taking a much larger unit than I'm using because of how amazingly stretchy she can get but it doesn't make her any less pleasurable to me and I can tell by her gasps, groans and goose bumps that she is more than fine with a smaller man working his magic in her mayhem.