We are currently testing an RNAV/GPS approach to R26L at Gatwick (EGKK). I have completed the sim training and the aircraft FMS's are loaded with the software and ready to go. The initial approach minima will be 700MDA (500MDH) and the guidance is both LNAV & VNAV. In the tests we left the ILS displayed but engaged Autopilot in LNAV/VNAV. The program has a clever submode that "opens" the speed window on the MCP to allow pilot controlled speed and config changes. The tracking was so good that at decision there was a perfect match between the GPS derived position and the dislpayed ILS.
It is important to keep POS page 2 displayed on at least 1 FMS to monitor RNP limits.
No doubt that as experience grows the landing limits will reduce to match CAT 1 ..............