I've been using my ancient LaserJet6p with a JetDirect server box for ages now and it's a workhorse. It just won't die.

It probably should be on a remote controlled switch to reduce its idle energy usage, but holy crap these things are made to last.

If I'm not mistaken, it also takes some special SIMM ROMs, but I've just been using PCL mode to send pre-rasterized data to it and it Just Works. PostScript has always been a bit of a gamble and more often than not I just end up with 100s of blank pages as it forgets to change the mode.