Ace will be Ace whether he's Ace/Une XD...although its a little frightening to think of what he'd be able to get away with as a girl...or that Une would most likely wear *less* than Ace what with a bikini top and probably midthigh shorts...(at least the guy shorts he wears reaches to his knees..almost)

...Ace's probably happy he's a guy though...can you imagine the trauma Une would have gone through explaining to Luffy about guy&girl differences especially when she's going through puberty? Awkward won't cover it XD