I picked Campbells SoundLogic combo board because on one board it had support for everything I needed, DC out to control VFD speed, MPG inputs and relays for my spindle and coolant.
The only rub was the documentation at the time was a little spotty and the speed control voltage isn't quite as solid as I would like it to be, but it works. I beileve they have reworked the speed control voltage and hopefully the documentation has improved.
My motor performance is very smooth and the only time I've lost steps is in a crash, but that's when you want to lose steps. I have a BP sized mill with big honkin' 42 size steppers. I use 60 ipm max on X,Y, 90 ipm on Z. I could probably bump my speed up with a higher supply voltage, I'm running about 2/3'rds of what the motors will take, but for what we use the machine for (prototypes, small production runs) we can live with the current speed.
Paul T.