I don't think the MKS is a coreless motor though. Also, what's the speed of the MKS at 6V? Which model are you looking at?
Right now I'm leaning toward Savox. Coreless, Brushless, aluminum case, titanium gears... The model is 1258TG. It's the same servo as an "Align" model. Hardcore heli guys use the Align brand.