I can only speak for solo sex, but: never on a full stomach. It just doesn't feel good. I usually don't masturbate when I'm really hungry too, but that's because I'm busy changing the "really hungry" status.
I don't like to have a really full stomach before sex, too easy to get a cramp - like don't go swimming withing 30 minutes after eating. LOL No, actually have a really full stomach makes me feel kind of sluggish, which makes it hard to feel sexy and be mobile enough for sex. A lot of times I need a snack afterwards though. My go too after sex snack is string cheese.
I agree with all you guys above. Can't have sex on a full stomach, just feels bloated and gross. I don't have to eat right after, but sometimes the hubby likes a snack after and I'll steal a bite or two of whatever he's having.