I've just emerged from reading the US FAR/AIM (sad, but necessary towards the FAA IR). That has some stern warnings about use of GPS, and some very enlightened ones.
RAIM is NOT the same as DGPS - your panel-mount IFR-approved GPS cross-checks itself against "spare" satellites and yells if it thinks it's going skewed. Your handheld/yoke mounted doesn't. You'd get into hot water rapidly using a handheld for navigation in the US.
I've sat in the jumpseat of an IFR commercial flight using enroute GPS, and it was most impressive. Cleared direct from Stansted to Düsseldorf, just like that. I'd like one...
But meanwhile, keep practising the NDB holds, just in case. The CAA might get you on "lacking in airmanship" otherwise!