I honestly don't think the new weapons they've introduced have been overpowered. They just fill roles that didn't exist before. Infiltrators could either snipe or use a pistol, so they introduced SMGs. Shotguns were a completely new class of weapon that are only effective in certain situations. The empire specific anti-vehicle weapons didn't really affect anything (other than the phoenix was truly OP for a week or so and is now absolute garbage).
Other than the fact that NC maxes are absolutely useless outside of point blank range (and anti-vehicle maxes from all factions being pretty gimpy in general), I don't think the game is all that unbalanced. But that was just introduced in the last patch with empire specific max abilities.
Except fuck one shot sniper kills. If you play a sniper infiltrator, i hope you die in a fire.