+1 for EOS 3.
The 1N has pretty basic AF and very basic flash by modern standards, the EOS 3 has the same pro layout but with the 1V's AF system and modern era E-TTL flash metering (it will work properly with any EX or ETTL guns you have for your DSLR)
It's also a bargain just now. The 1V is better, but the 3 has 99% of the 1V's DNA and costs a quarter, a third, and is also more likely to have had a cherised life as an amateurs pride and joy than a pro's workhorse.
You get EYE CONTROLLED FOCUS, which if you spend time setting it up is just about the best thing ever.
A lot of folk slate the Eye-Controlled Focus, but they had funny eyes, and if you don't like it there is an off switch.
It feels a bit light in the hand next to a 1V, but then my car feels a bit light in the hand next to a 1V. It has a distinct shutter noise (or mirror slap noise, horses will bolt, birds will fly away en masse)
I wouldn't buy a 1V nowadays. You would want to buy a new unused and keep it in its box, if you want a user which to almost all intents and purposes is the same camera, get a cheap but cherished 3. Use the strap stopper for the viewfinder blind, the EOS link software probably won't run anymore. Hey presto, your are back to the 3.
The question isn't should I buy one? It's why haven't you bought one already!
I don't know what you are using just now but do bear in mind that as a pro-orientated camera with weather sealing the 3 lacks a built in flash. This may not be that big a deal. If you want a film body with built in flash then buy as recent as you can, buy a 30v (again with eye control, but built in flash, laid out more like a x0D series)
Good luck with your 3.