I did. I was intrigued, particularly after a session in a friend's studio, equipped w/ the real thing - which is amazing.
I liked some things about it - the simplicity of the old-school approach, you know... EQ and (very good sounding) compression and saturation accessible w/o messing w/ plug-ins. I imported a song I had been working on and rebuilt what sounded like a better static mix in less time.
But, in terms of navigating, it feels clunky, rigid and "heavy" (just launching it, my CPU fan starts spinning loudly, something which almost never happens w/ Logic, even running a 50 + tracks mix). I wouldn't want to deal w/ fancy automation - or anything too fancy for that matter - in MixBus.
This and a few other things contribute to the fact that I really don't see myself creating or even just recording and editing into it. It just feels so slow and hard to move.
Don't know if this ever happened to you, but after a while, I noticed that my wrist was getting painful because my hand was all tensed and I was actually pushing on the mouse if I had to lift something very heavy...
Obviously, you have the option of using jack audio to route the audio from your DAW into MixBus. To me, the actual benefits of MixBus weren't worth it.
If I'm to use another DAW to record and edit, I'll most likely start messing w/ automation, plug-ins, pan controls, grouped some things and routed certain other things to busses before I start to mix, anyway, as part of the creative process.
When I reach the actual mix stage, the basic building blocks are there. Having to handle duplicate mixers and 2 different layers for the same mix would be counterproductive.
For Sonar users, who have access to built-in console emulation and Pro Channel, I hardly see any benefit, beside adding one more color to their palette.
My 2 cents...