Come over to my place and tell me if you like 2 channel or surround for music. A listen may change your mind. It will also illustrate to you what Ian strived so hard to achieve with the family of curves.

I don't understand what you mean by tweeter in or out.

M5HPs are not too big for height especially given your 9 foot ceilings.

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