In most pilotage situations, I don't bother with the GPS. I use a pelorus and "60 D Street". I use it to compare my DR to my lat/lon a couple of times a day, but I find that when I can see the coast, it's most useful for ETAs, compass headings and cross-track estimates.
I don't assume it correct, but do assume it's "correct enough". Offshore, I have the sextant, after all, and truly gross errors are going to become apparent pretty quickly, particularly if you've been charting your course on paper. Besides, hourly fixes gets me off the deck to reapply sunscreen and to rehydrate!
I also agree that radar makes a nice rangefinder and that a few classes in how to use it can make a big difference in how it's used (self-evident, one might think, but I've seen it used incorrectly on more than one occasion). You can, after all, avoid another boat easier than you can avoid a penisula with a strong current wrapping around it.