I use 8.6. It works well.

9.0 may or may not break my cheap USB modem and costs $$$ and doesn't seem to run any more apps I care about or make my machine go faster (though I guess I get a copy of iTunes, whoop de do when you have Sound Jam). I may upgrade some day. I doubt I will go with X on this machine due to the pain of installation and the upgrades needed (IDE card, printer, ink carts, some new software, still a G3, etc)

My Centris is still at 7.5.5 though (mostly sits unplugged).

At least my S900/G3 will rip a CD reliably and encodes about 6+ times faster than the PC.

I sent in a message to Jemplode help and they reported back that I need Java SDK 1.2 (soon 1.3) or later and MRJ 2.2.5 is only Java 1.1.8. I tried downloang the appropriate pieces that add a little back functionallity, and it got farther before I got an error. Apples position is use X if you want a current version of Java.