Chuck,
The question was how to improve his VFR nav, not which system is best. If he goes back to basics he'll learn something as you and I did in the old days; drift sights, astro compasses, Gee, H2S, doppler, decca, loran etc.
I always carry a GPS, but seldom switch it on, its too much bother most of the time. Part of the joy of flying is that you don't need most of the gadgets the latter day PPL depends on. A little basic nav and the'll realise they don't need them either.