In ceiling M3s should work very well. I would have gone that route in my room, but with it being soundproofed, it would have been a huge hassle to get backer boxes up around the area where they would have gone into the ceiling to contain the audio as much as possible. Plus I would probably have hit a ceiling joist or piece of hat channel right where I wanted them to go, so I opted for on-wall M3s that I mounted on my ceiling.

Again, the in-ceiling M3s would have been my 1st choice if I could have made them work as they are a much cleaner look and the aimable tweeters help (although the woofer should technically be angled too).

2-M60s, VP180, 8-M3s, SVS 20-39PCi, DIY Sub, 8-Shakers, JVC RS45, Anthem MRX-1120