Which Lisp versions do you use SLIME with?
OpenMCL 0.14.x Allegro 6.2
Which Emacs versions?
GNU Emacs 21.3.50.2 (powerpc-apple-darwin7.0.0)
How well does SLIME work for you?
I'm a fairly casual user at the moment, but I've not had any problems with it on this platform so far (I had some issues on Linux, but I think they were mainly to do with a screwy Emacs installation).
Keep up the good work! Cheers, Ian.