for what it's worth:
haven't hobbied yet. i've been with women of varying ethnicities, sizes, heights, with/without children. women have told me that they sometimes use "dick math" to determine a guy's size without having to see it. they say sometimes it works and sometimes it doesn't (in both directions). i've tried formulating my own "pussy math". at first, i really did think women who were bigger in the hips were generally looser. this has not been the case in my experience (quite the opposite actually). i can't say that any given ethnic background, sexual experience or childbirthing really added up to anything consistent. I can say that taller women typically can "handle more" than shorter women (duh). the "most trimmed" girl I've slept would could take my whole fist and wrist inside her (i'm 6' and can palm a basketball). She had 2 kids and her exhusband was a lot smaller than me. however, she was one of the freakiest and got off to a lot of stuff. the more plump women I have dated seemed to have the tightest of the group. my wife is very tight and depending on her mood it can get tighter. however, i did go out with a true bbw (probably ssbbw) and while we had good sex, in order to get her off, I had to put 2 hands inside her. i could never understand that one. dated an average sized girl who's ex husband was bigger than Lex the porn star. she only used toys as big (or bigger) than him. her pussy was literally like a 2" pvc pipe. we worked on the tantric sex way of doing kiegels for a while. she lost interest lol. she did have 1 kid.
from my limited experience i say generally:
1. women with children on average are looser
2. women who are literally big (5'10">) and weigh more than 250 lbs are looser
3. even though women can be loose, they can still get off really easy
4. some women produce a LOT of lube, which makes them feel loose
5. just because they are petite doesn't mean they are tight
6. just because they are plump doesn't mean they are loose
7. chubby women shorter than 5'5" typically have a tight pussy
when a woman does kiegels all the time, there's a good chance that ever thing above may not be true.