Actually, I have never tried to get enrolled in these programs (although I am a registered developer).
The main point for me to get registered was to get help directly from those nVguys (i.e. explanation on how to use new extensions or confirmation of driver bugs) ! I must say that when I did it, Cass and Matt were not on this board yet…
These days, I visit the registered developer web site less often: almost all the material I need is on the public site and the “private” drivers are older than the leaked ones (which is a bit frustrating I must say… that takes me once again to GL_NV_vertex_program… ). It still happens that I contact someone at nVidia directly for specific problems but I must say that almost all my questions are answered by Matt and Cass (you see, I reverse the order here so that none of them get jealous of the other !).
But if your point is to get involved in the programs you mentioned, I am sure it is worth getting enrolled !
I am sure Cass will help you.