Software KVM? Prevent Mouse movement on main PC?

Hey all,

I've been tinkering w/ software KVM solutions (Synergy, Multiplicity, Input Director), and all of them seem to suffer with the problem of the mouse still moving on the main computer (IN GAME ONLY, does not move if on desktop) when I switch to the slave computer(s). This isn't a huge issue in games like WoW/etc. but I'm using it in Battlefield 4 while in a helicopter. Unfortunately, when I move the mouse on the slave (repairer in helicopter), the chopper leans the direction I'm moving on the slave computer. The pilot is the main computer, which I don't want to move while the slave computer's pointer is moving.

Again, this only happens in game. I've done a bit of reading online and it appears that it might be a limitation of software KVM, but I'm looking for any advice.

I will invest in a hardware KVM if need be. Can anyone recommend one with little to no delay in switching? With programmable PC switching hotkey(s)? Again, I will only go the hardware route if the mouse mirroring problem is not able to be fixed.