One of the problems with any kind of control mixing, whether it's electrical or mechanical is that it has to be optimized for one weight and CG.
For the UH-60, that optimization was done for the original design weight and CG - the inter-relationships between cyclic, collective and pedals were such that a pedal turn at that design point resulted in only a yaw rate. If you were not at the design point in terms of weight or CG, you got some strange effects- moving the pedals resulted in pitch and roll movement of the nose- lighter than the design weight, and the aircraft moved one way - heavier than the design weight, and the aircraft moved the other way. Not a lot, but enough to be noticeable.
So if you're going to do electronic mixing, it would be wise to add a weight/cg bias capability.