Logical thinking tells me the following :
G-code gets sent from Mach3 to the Servo's by means of pulses, the servo's then sends these pulses to the motors..... since the servo's currently have no S Curve or anything else fancy, the motors move according to the pulses received by the servo's which was sent by Mach3.
So in essence when you add a Motion Controller like Galil/Kflop , the g-code (pulses) gets sent from Mach3 to the Servo's, the servo's pass the information on to Galil/Kflop, which then adds in their "special magic" and pulses through the commands to the motors.
Since this is all a open loop system Mach3 doesn't really match up what it had sent originally and just excepts the fact that everything is 100% (which it is if everything is setup properly,or within your "tolerance" set in Galil/KFlop)
That all being said, this still doesn't add S Curve functionality anywhere as Galil/Kflop doesn't have that feature. I know Galil can handle the info for S Curve, but that needs to come from the Servo's.
AFAIK in order to get S Curve to work on my Servo's I need to make use of a PLC unit....... this is where it gets confusing for me hehe.
I'll do some more testing this weekend jrobson as I haven't had time for it just yet..... will keep you posted
This is just all theory, but sounds logical to me.