I have a 11 1/2 year old z3100 and it works perfectly after replacing my spectro with one from China.
My advice is if you enjoy working on electronic equipment and tinkering with things go for it. Parts are available and the knowledge base is there for doing the work.
But if you are like me and have little or no patience or talent for this kind of activity don't go there. Almost any service call will cost you way more than it is worth. And you never know how people take care of their printers or what kind of surges in electricity have gone through them.
But if you do get a price that you can't refuse make sure you sit there and do print tests with it. First thing is to print out the diagnostic pattern and then do a linearization. If the seller won't cooperate just walk away.
I use mine on both a Mac and a pc. When my pc updated itself to windows 10 I had nothing but trouble though it did work fine for about a month until updates messed it up. When I reinstalled windows 7 everything went back to normal.
John
It does run on Mac. My 2010 Z3100 did until main PC board failed last October.
Still pondering a new Z2600 (around 1700 € here).