Questions about certifications?

[killercam]

I have been wondering about the certification and how its gonna effect the game. First off for every cert you unlock does it have an negative effect as well? I was also wondering about balance and the whole theme of the game seeing as each faction is suppose to play a bit different but for example im Terran and i cert so i do more damage but in contrast my speed goes down then i would basically be NC in terms of play mechanics. Now if certs do not put a negative effect then how would a newer player be on the same playing field as a vet?