Does using the geo-pointing module negatively affect the ISM capabilities?

Yes, the geo-pointing module (GPM) takes the PTU position (six axes) and the desired pointing location (three axes), calculates the pointing direction needed to connect the two, then commands that pan and tilt angle once. If the PTU is not actually at the programmed PTU position, then the pan/tilt angles calculated will be wrong. If the PTU moves after pointing to that location, then the PTU will be pointing wrong.