Hey zipper, congrats on the m60s! You are going to be one happy camper, I'll betcha.
Let those babies break-in and then you'll see how good they really are. Did you order for their CC too? My m80s are breaking-in nice and slow and its sounding better and better each day.
I looked into their models you mentioned and they are too big for to make a rear CC for me 'cause I intend to hang them on a wall (suspended).
I contacted the axiom techs to see what they would suggest and they recommended getting a pair of the Q8s for the rear center. I can see those fitting well since they are powerful and small/light enough to fit up there... and they are beautiful sounding speakers too. I haven't made up my mind yet. I'm still shopping to see what else might be out there that's worth checking out. If you can think of some other brands/models let me know. Someone suggested I check out the Wharfedale's rear CC too. I don't think the rear CC need to match with the front speakers...do you? I'll keep you posted. Enjoy those m60s.
jzac