It makes a big difference. As a 33 against 34s, many ohks would leave the other player barely alive, say flux grenade, shotgun to the face, 2 melees, rockets, snipers with low attack. Not as bad as ToO, not indestructible, but toughe enough that even one level difference puts the lower leveled player at a clear disadvantage. Nothing wrong with level advantages, but I hope this is all intentional and not an oversight.