There are some unforeseen side effects, 8D0907551M software totally ignores MAF (regardless of MLOFS value), same thing happens on 8D0907551G. Using 8D0907551F is even worse, not only MAF is ignored but cam adjustment reports some fake electrical errors.
Neither of those makes sense, unless you are using a BEL harness with the M box. Do not do that.
My ECU was pulled out of an A6 2.7T Tiptronic and it's currently running what I believe is S4 6sp software, if there are some side effects I just haven't noticed any.
The ECU itself is swappable, that isn't the issue. The issue is using a file in car with the wrong trans type.