i've done a final mix, but i wouldn't call it mastered, i've also mixed to it from a 16 track. i don't use those 3 wreck buttons tho. i tried them many times, too weird.
i've gone from a 16 tk thru a pro vla to mr8 also
i like mixing to it since i know from experience what the levels are on the meters and what they will be on the final.