I have an X83. It is slow, but under 10.2 Lexmark's new drivers do fix a problem I was seeing with the black and color inks slightly out of registration.
If you really want to make it go slow, do 1200x2400dpi!
I have it hooked up to a sawtooth 350Mhz, and noticed that the CPU is always nearly maxed out when printing. Guess Lexmark's driver just prints a bitmap to the printer over USB. Don't know how fast your machine is, but this might be a factor- I'm going for a dual 800MHz card soon, will be interested to see how that helps.
The print quality is very good on this thing, and it was dirt cheap, so I put up with its speed issues and a bit of quirkiness from it. YMMV.