I would think if you are using the PP then you will either have to use either electronic gearing in your drives or low count encoders on your motors. I personally would use an external device as it would mean pulserates would not be limited as with the PP.
As for VB versus PLC Ladder, personally ladder for me is much easier and much more powerful. Obviously macros are still needed to talk to the PLC but they will be simpler affairs.
Hood