I approched this test in this way. I found a section of the song that was consistant in level and with less instruments and was able to hear the stereo spread good in that section. This made It easier to listen to each instrument and vocal. The only thing I can hear clearly is that BTB is brighter than BTA. That's what I hear. You can hear it clearly on the right panned guitar. The stereo image seemed to stay the same as far as I can tell. Which is Sonar and which Mixbus I couldn't tell you.
I'll take a guess and say BTB is Mixbus. Either way I like Mixbus and Sonar and enjoy both for what they do.

A few things I have  observed so far.
 
As Mix B is the obvious upper mids and highs increase over Mix A, it stands to reason it might be a fraction louder. I found by adding 0.75 dB to Mix A then it actually compares a little more closely on my hardware VU's to Mix B. It is vital to get rms readings between both waveforms within a fraction of a dB if possible.
 
This is a comparison only between Mixbus and Sonar console emulation.  Studio One has a very interesting console shaper now and the tube setting can really push those upper mids and highs very easily. In fact stronger than Mixbus in that mode. So it might be interesting to see how that would compare. 
 
If Mix A is Sonar with a raft of console emulations then it does not sound like it. All for what? Mix A is just a bit dull. Whereas Mix B just has the extra upper mids and highs. (without effort) But then I could be wrong too!
 
Mix B would be a great starting point to mix from that is for sure in terms of raw tracks. 
 
 
 
 
 

Mix B has more depth and is slightly more defined.
FWIW, when you sent me links, the first thought was A - for Alisa, B - for Bapu.

My preference would be B, but only marginally so. I'm still not convinced it is worth the effort of exporting the tracks from Sonar and then mixing in Mixbus, if that is the one done in Mixbus. This mix, as it stands, already needs so much work that the "difference" would likely disappear due to other edits while EQ'ing, compressing, etc...
 
I am, however, glad that Ed shared these. It was great to be able to hear the to tracks...
 
Regards,
Dan
 

Looking forward to the results.
 
There is no way I am taking part though as my ears (and skills) are crap.

synkrotron
 
... as my ears (and skills) are crap.

As are mine. But I'm going to give it a shot anyway. I got a 50/50 chance!
 
 
As most have siad, B seems to be a little brighter/louder. So I did like Jeff and adjusted the volume on B down 0.6db. Even then I could still tell B had a little more "openess" to it. But only in the more subdued parts. When it got loud and going, I couldn't tell any difference.
 
Disclosure: I have Mixbus but have never installed it. So I have never used it.
 
And here is my answer: I think B is Sonar!

Soundwise
Mix B has more depth and is slightly more defined.
FWIW, when you sent me links, the first thought was A - for Alisa, B - for Bapu.

I would say that A is Mixbus as it provides a saturated, fatter sound with the glue factor. This is based on the description of what Mixbus is supposed to sound like. Not to say B does not, just that A has more of it. 

Just listened, but not yet read the other's comments above ... I got a clear preference. Will see if it turns out to be Mixbus or if I can save the money on upgrading to v4 (and invest in an hearing aid instead) ;-)

Rob[atSound-Rehab]
Just listened, but not yet read the other's comments above ... I got a clear preference. Will see if it turns out to be Mixbus or if I can save the money on upgrading to v4 (and invest in an hearing aid instead) ;-)

Why not go ahead and post your preference. 
 
It's not a bad/good or right/wrong thing.