I don't understand the fixation on moving rigs. They don't move that often, and there aren't that many of them. I don't often fly around in IMC at less than 500'. The only time I'm that low is when I'm on final approach, and then I'm required to avoid all radar targets by 1/2 mile anyway. Moving rigs are just red herrings in this discussion. They will likely never be in any database, and don't need to be. There will always be obstacles not in the database, and blindly relying on having them is begging to die.
I agree with Nick. Just because a system isn't perfect (and no system is) is no reason to reject it. If it's even marginally better than the one it replaces, why not use it? Cutting off one's nose to spite one's face is ridiculous. EGPWS, while certainly not perfect, is better than anything else, so why refuse to consider it? Work for improvements, certainly, but rejecting it out of hand just because it can still be improved is just silly.