Well, in the short time (hours) that I've been using OS 9.0.4, there is one thing I've noticed: it takes up less RAM. While 9.0 was hovering around 21.5, now with 9.04 the system went down to around 17.5. This was a straight install, I disabled no extensions, RAM usage went down 4 meg... Whether this is unique to my case (PM 7200/90) or whether Apple decided to fiddle with what stuff it reports as being in the System Heap, I don't know. I've had no problems yet though...