Mixbus is excellent.
I just got a second hand Macbook Pro Core 2 Duo which is great for audio production. I use Linux as well as OSX including AVLinux but needed a new computer. I decided to go with a Macbook Pro so then I could run Mixbus and a few plugins I want to use. We want Mixbus Linux but I know this isn't really a Mixbus forum. I actually prefer Linux as an OS.
One thing I was wondering about was the Lexicon PCM plugins. Does anybody know if these work in Ardour OSX? Do most AUs work or are there problems? The Lex plugins are very expensive but they are the best plugins end of story. Superb reverbs. You have to have ilok to even test the demos but I may do this. I was considering a second hand hardware Lex but the plugins make more sense.