We put a lot of thinking into that topic when we were to equip our shop. Sales reps showed us a lot of used and new machines, and being newcomers, we were always horrified by the condition of the used machinery, and the environment they have been running. That left us with only one choice and we went with brand new printers.
Now I see a totally different picture. Those run-down machines are still churning out pages and the companies using them make a lot of money on the production, since there is no lease. Some of them even abandoned their service contract and somehow manage to keep the printers on a production-level condition.
Honestly, BW technology is absolutely mature, and if you don't need inkjet, most of the used machines, which aren't older than 6-8 years, will fill the bill.
Color production is a bit different, I do see progress here but mainly on the practical side of daily operation. New printers always have something better, eg. better front-to-back registration, easier setup, tighter color control. Still, 5-6 years old machines produce acceptable and sellable printouts, their owners beating us to earth with pricing. Again, no lease.
What I feel is any used machine can be a workhorse if you use it for the right product, and the manufacturer still support that particular model.
Just my two cents.
