These GPS discussions always see to attract the same big hitters who are no doubt very current, capable IFR rated pilots who have all the toys. But I can't help thinking that since this is a private forum, most of the flying done by readers is VFR touring. Correct me if I am wrong, but the main attractions of flying are enjoying the view and the freedom of all three dimensions. That by definition means you are looking at the ground - transition to IMC is not desirable (or indeed an option in many cases). Moreover, because you are doing it for fun, you decide where you are going and what you want to see along the way. It makes sense then that navigation is done by reference to ground features.
This private forum attracts people with all sorts of flying experience/aspirations in a huge variety of aircrarft. But some of the regulars on GPS topics are pilots whose flying is on a very different level to that done by the majority of those on this forum. IO and Chilli et al, you are very correct in your opinions for the sort of flying YOU do, but they may not be so appropriate for the flying done by many contributors on this forum.
For the record, my opinion is that VFR flight means that you navigate using a chart and the mk1 eyeball. IMC is to be avoided like the Grim Reaper. Therefore MSAs and radio nav aids are of little interest. A GPS is a great box of tricks to confirm your eyeball navigation and to give you a range and bearing home. I know this contrasts with you big hitters, but it suits the sort of flying I do and no doubt the flying others do too.