i dunno, i personally think its a pain in the *** another thing about those suits is if you grow a little/ put on a few lbs, its hard to zip up in the back.
The two piece underarmor at least gives you that flexability. That and if you are at an event and its over, but you're hanging out afterwards, you can lose the top portion and just rock short sleeves or what have you, instead of having the be stuck in a full body suit, and or have to change.
plus at the price of that you might just be better off with underarmor cost wise