Only comparison I have is that I vastly preferred running into the loop of the Randall RM50 or RT2/50 as a power amp compared to trying to run modules into the FX return of my Dual Rectifier.
The Best combo I've heard (but not owned) was M4 running into a VHT 2/90 (might have been a 50...long time ago.)
VHT power amp is the shiznit.
I can say that the MDA board with the pot pulled is night and day different to stock but whether that's better than another power amp?
The Foglifter change is far more subtle but makes the controls more usable.....not sure exactly where it positions the values. Whether it's better, is again up to your ear.
There's a new Salvation MDA that has a better stock mode too...