It's a good idea, though there are a couple of problems: Flinch mechanics, if applied, should apply to all players. Flinch mechanics generally favour high rate of fire weapons because those weapons can stack on much more flinch. Planetside 2 used to incorporate flinch mechanics, and that caused an entire faction to significantly underperform the other two factions. Since then, flinch mechanics have been nearly entirely removed, and the game improved a lot as a result. Furthermore, flinch mechanics, if not well balanced, can give too much advantage to initiators.

Maybe the flinch should only be activated after and during consecutive hits and only activate at a close range to give more of a playing field with AR vs. shotgun. I feel AR should be able to have more CQC to round it out. The AR should be effective in nearly any situation, but not excel in any one area. Pulse should excel in mid range and scout in long range. They mostly do. Shotgun of course should be king of CQC, with it's powerful blast, but as it stands now, it's alone. Having a primary that can contend with it at least slightly in CQC is a must, and that primary would either be something like an high ROF AR or SMG