I ended up sucking it up and buying a MAMS and its the best brake / adapter I have on any gun. Running without a can is crazy, the gun doesn't budge. I wouldn't buy a MINI version of the QDC for a shorty, my mini is loud on a 16 inch SR15. I'd get the full sized 556 KAC can. Just my .02. But I'd get it.
If you will run the gun suppressed 100% of the time, maybe the MAMS is not needed. I do think it did quiet the gun a bit moving to the MAMS though so...
PB