I've got a One10 and, based on what I know about the GK MB500, I reckon this should be a great little rig. Although rated at 250w, Alex at Barefaced assured me that the One10 will handle "500 clean watts all day long'' so the <400w that this amp probably puts in to 8ohms will be a breeze. Actually we use a TCE BH550 through a One10 at Gillett for demo's and it easily handles the big fat sounds that our Contour basses put out.
GLWTS!