I have a New F-1 and had an EF as a second body for a while.

The New F-1 has a better mirror damping system, and I've tested it against the EF with MLU. While the EF does better with MLU than it does without MLU, the EF with MLU is not necessarily better than the New F-1N in my experience.

The big attraction of the New F-1 for me is spot metering, but it's hard to find the focusing screens that will give you that option. If you want spot metering, but can't find the focusing screen, you might look at a T-90.

The EF does have a faster X-sync speed (1/125) than the New F-1 (1/90).