G5 has dual channel AT and dual autopilot, CAT2 operation is possible.
More interestingly, EASA is working on certifying an approach continuation procedure to 100ft on CAT1 ILS approaches based on clues from the FLIR installed in newer Gulfstreams. No idea when it's coming, but that should mark a significant operational advantage, as we bizjockeys tend to operate to airports lacking CATII/III equipment...
Somebody told me that in the US, this procedure is already in place for part 91 ops, but haven't verified... anybody?