Ok, I've been enjoying this thread and carefully paying attention to what is being said.
First one needs to remember one of Newtons laws "every action produces an equal and opposite reaction". Unless you are firing something like an energy only weapon, there is going to be force exerted to move the projectile out of the weapon. That same force will be excerted back against the weapon and henceforth against whatever (or whoever) was holding the weapon.
Normally, like on a planet with a reasonable amount of gravity, this isn't too much of a problem. The person holding the weapon (since that is what we're talking about) can "brace themselves" on the ground thanks to gravity.
Unfortunately in space there is no gravity. Even if you were standing on the hull of a ship, if you didn't have something holding you to the hull of the ship, then when you fired a projectile weapon there would be nothing to hold you in place. The force may not move you much, but it would get you moving.
The ideas of a compensation system (to counter the force of the weapon being discharged) is a great idea. In fact a system that just uses the stars to keep you stable would work (system notes the stars in relationship to your current position and unless you used the suits controls to chang your position, it re-establishes you back to your position relative to the stars).
The biggest problem for such a system is the depth of the programming needed to make it work effectively.