I am using a G4 Mac Mini, for just about everything except for digital soundcard modes. I cant find any Mac Software that I like for those, so I use gmfsk on a linux box with the display exported to the Mac.
For logging I really like using jLog http://jlog.org
it's written in Java and is cross platform -- Mac, Linux, and even Windows.
Running a Linux/Mac household, where the only windows are in the walls where they belong.