If you talking about max efficiency from ATWH then you shoud size your emitters bellow 100 F supply. You could reach 400 % That is why radiant slab is the way to go or combination of radiant wall and floor.
Personally I think Enertech and Taco system M is a bit overpriced. I would definitely go for Stiebel Eltron for $13000 or MBtek $10000 FULL HYDRONIC PACKAGE.