If you mount them via ceiling mounts, you will lose bass response. I'd mount them on the wall with their tops 2 feet from the ceiling...3 feet max. You want to make sure no one will hit their heads on them.

Your dad may not want to wait for your M100s. He may end up with actives before you. smile

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated