I'm 15,000 miles into a Stage 2 tune from MRC on a 2010 DSG S4, now on 67,000 miles. with absolutely no issues whatsoever.
Included in this is 4 or so trips to the Alps and Austria, the latter involving half and hour of 140mph on the autobahn and other less lengthy sections at the same speed.
MRC taking the time to tune the car properly with dyno time cannot be overlooked, if you have the patience, wait for MRC.