The only glaringly obvious issue I've seen revolves around sidearms. I've got two issues.
First of all, they draw way too slowly. They're faster to pull than the base reload time for any weapon, but it still seems way too fast to draw down on bad guys. I know that Loadout Pro's third-tier effect makes the draw faster, but I still think that sidearms should be quick enough to alternate off to when you're in tight with someone.
Solution: Cut down the draw time of secondaries. Make attachments slow down the draw to encourage players to run clean sidearms as a counter-balance, and then make Loadout Pro III cancel out that attachment slowdown instead of its current effect.
Second, I've been killed a couple times by what seems like a bug. Upon emptying my Feline, it entered the reload animation, and would not begin the sidearm's draw until the animation was roughly two-thirds complete. I've only encountered this with the Feline so it might be weapon specific, but it happened to me a couple times.
Solution: Drawing a sidearm should always interrupt a reload animation, or the transition to the reload animation.
Thanks, and great job, CryTek!