In any party situation I'd prefer WHM/SCH over 2xWHM or 2xSCH, they have a good synergy... 2xWHM can get very cure spammy in some instances, though since I main WHM I've never gotten a chance to see 2xSCH, so there is some situational Bias for you :3

I just have to ask for 2xSCH parties does Fey Illumination stack or no?