The X-700 final check is tipping the scale for me.
Means you can use lenses that might have slightly heavy blades (in one sense or the other) and means you can use older stop-down lenses without thinking about it.
Program is very nice. It not called P(rofessional) for nothing. It makes the decision you’d normally need seconds to make, instantly.
I can live without having to see the time in the viewfinder. I never actually used it on my 570.
I usually use M as “shutter priority” anyway, so I know what speed it is.
Slow sync can be quite easily modded on the 700, but really 60 is what you want most of the time when shooting in dark conditions.
Still some ambient fill, but the shutter speed is fast enough to stop handshake blur on it’s a own without ghost trails.
I have both and I reach for the 700 most of the time.
If you absolutely need the time in the finder, the 300/370 is a plentiful and cheap alternative.
The only things missing from 500, in the 300, is TTL, stop-down and data back contacts.