I'm replacing my MBP with an iPad, 64GB/3G. Going to use it as my primary device. I already use a household iMac as the central repository for media (and syncing) so that will remain in place.
But to be clear I basically don't "use" the iMac except for the once every week or two when I sync my iPhone. I don't expect that to change. Other than an occasional sync of the iPad, I won't do any work on the iMac.
I'm embracing the iPad whole hog.