.....all of the weapons in this game and most of the fits (probably even scouts) would be perfectly balanced if the proficiency damage increase and damage mods were removed. 1 complex mod plus proficiency 5 is a 25% damage increase to a weapon.

Want balance? Reduce the range and ammo carry capacities of all weapons, replace damage mods with weapon range amplifiers and ammo capacity upgrades, and change proficiency to something unique to each weapon instead of a flat damage buff. Even if you just made the damage buff work for the weapon's strength instead of a flat overall damage increase it would be worth it (i.e. SMG's & combat rifles get a buff to armor damage per proficiency level, ScR's and lasers get a buff to shield damage per proficiency level)......

The higher a weapon's DPS, the bigger the buff it gets from proficiency and damage mods. This would cut down the DPS of all weapons, however more than that it would bring the higher DPS weapons down closer to the level of other weapons. In addition, it would make choosing whether to go for armor or shields much more important. You'd also have to choose whether you want to carry more ammo, have better range, have more HP, passive scan people within your scan radius, or have a larger scan radius. The low slots already have many options, high slots will finally have viable options.

If you couple this with fixing passive scanner modules (if you make them viable you also make range amplifiers viable), thus giving you 5 viable high slot modules [shields, scan range amps, passive scan precision amps, ammo amps & range amps]), this game could be balanced pretty much for every weapon in the game instead of just for the AR's. Not to mention 10x more diverse in fitting options. It would also make dampners far more important with people passive scanning without giving "YOU HAVE BEEN SCANNED" messages.