Does the triathlon you're doing have a net gain of greater uphill than downhill by a lot? The reason I ask is because the weight of the bike doesn't really matter as much in a triathlon unless the previous question is answered with a 'yes'. If you're going to do anything, go aero. Clip-on bars, aero helmet, proper fit, deep wheels. Unless you've got extra cash, want the bike to look good or your drivetrain is crapping out.