First of all if there is a post about this I apologize .. I went through 6 or more pages and didn't see anything.
Ok back on to subject. To me these two classes are more aligned to making credits (last time I checked credits don't have a faction), depending on how you play them. If you play them light (fighting for the good of the galaxy but still wanting to get paid) or dark ( just wanting to get paid and create some carnage on the way).
It seems to me these two classes would be ideal to choose a faction through quest story line or at later levels through your actions.
As far as the balance of classes. God knows I see plenty of Imperial Troopers around, and plenty of Republic SIS agents...