the small tube is definitely wetter, even in small swells. i also find i can't sit on the tubes when running the engine - need to sit in the bottom. but it is lighter to manhandle, stows smaller, and inflates quicker.

of the two (big tube and small tube) i take the small tube along when cruising. not because i think it's better but because it's easier to stow. i actually use and prefer a hard dinghy, so the inflatable is just a 'backup'.