I have an MC Mix and an MC Transport and have been using them with TotalMix to good result.
I have found that, on occasion though, it just stops working and I have to:
a) delete TotalMix from (and disable) Euphonix's Mackie Emulation (in System Preferences)
b) trash TotalMix's preferences
c) reboot
d) re-enable Euphonix's Mackie Emulation, and add TotalMix
e) setup TotalMix for the surfaces again
It's usually good for a few months.
I have noticed however that most of the Mackie Control transport functions, used to control Talkback, Mono, Dim, etc. do not work with the MC Mix, but work fine with the MC Transport.
Hope this helps a bit.