is your question "would you update to windows 7 if you were me?" I agree with Blackhawk7188
that if you want to try it you should not wipe out your vista x64 installation, for many reasons.. but it is a good idea to try windows 7 because it has a new kernel, that is more optimized. as far as I know, they re-wrote the kernel and possibly other parts of the operating system, because they did some things wrong with vista ( it became a memory hog ).
but to be honest, since you have so much RAM, I don't think the memory savings of windows 7 are going to make a big difference for you, still it is worth a try to see if you like windows 7, if you always like to try the latest then you should give it a try and see for yourself!
for me I skiped vista all toghether, and since I was an XP user, windows 7 was a big jump in terms of interface and ease of use. but for a vista users, it's not a huge jump, the interfance is mostly the same, it is mostly the inside ( I.E. Kernel ) that has changed, so I think you won't notice a big difference... well at least not on the outside! but excpect windows 7 to perform better overall, specially on the bechmarks tests, since it has a new better written kernel.