At first, I think we'll see a flood of Light body types.
At first I think we'll see Op swarms.
Over time, it should all balance out, as players stop thinking "ooh, imma show off my awesome par- WHY AM I DEAD?!" and start thinking "I'll stick to a Medium - I still get to play with SMART, but I can survive a couple of hits now" instead. Or "Well, I like the parkour thing, but I'm just better as a tank - HEAVY!"
For Classes it'll be more like "Imma sneaky sneaky-WTF? WHY AM I NOT DISGUISED? WHO CAN SEE-" *dead*
This should turn into "Well, I'm better at tanking than that sneaky stuff - I'll go Medic/Soldier/Engineer and help out the team" and "Well if I stay with teammates, I'm not really that useful as an Operative, so I'll get no XP that way. And if I'm going solo, I get killed and also get no XP. Guess it's time to try something else."