I am currently using a McCormack DNA 0.5 DLX with Maggie 1.6 QR's. I love this combination. I'd say don't be afraid to go with your McCormack until it proves itself not up to the task for your room and listening preferrences.
My room size is about 16 x 22. I listen to a lot of chamber music, although I also listen to a fair amount of hard core orchestral stuff (Mahler, Bruchner, Shostakovitch). The DNA 0.5 does a much better job overall with the maggies than my previous amp, which had 2x the power rating of the 0.5. Only very rarely do I notice a little compression that I don't remember with the other amp. I'm thinking about buying another DNA 0.5 and biamping rather than give up the sound I'm getting now.