I started with a Soldier\Medic character discovering how fast you could grow XP with those classes.
Now I am more expert than the beginning but I find very difficult to get the same results with Tech\Operative, so imho classes are really unbalanced and Tech\Operative are much more frustrating in a fast-paced game like Brink than Soldier\Medic.
Being killed while frozen doing an objective (or mounting a very weak turret) gives no fun at all (and this never happens with Solider\Medic of course). Tech\Operative classes should definetely be rewarded more for what they do.
JMTC