John Roling writes up his experience moving a Domino 6.5.4 on Windows 2000 to a Domino 7 server on Windows 2003, in a total time of three hours.
So in the course of 3 hours, I moved an entire Notes server from one hardware platform and one OS to another piece of hardware and a newer OS. I then upgraded the Notes server to version 7. The only reason it took 3 hours was because the 60 GB transfer of the data directory took two hours :)This is one of the beauties of portable code. An NSF is an NSF is an NSF. Very straightforward, and removes a lot of the administrative burden of upgrading hardware. I'm not an expert, but from what I've read, I think John's dare is on solid ground. Time trials, anyone? :)
Try that with Exchange. I dare you.