I've been super happy with mine. I have a 7.2.4 setup with on-wall M3s and in-ceiling M3s, driven by a Marantz 7009. I actually hooked just two up and sat in between them and listened to some music in stereo. They image very well without any angling. The processor is using all the surrounds to 'place' sound objects in the room. I honestly haven't worried about angling the drivers. It would be easy enough to come up with a wedge shaped ring- but I'd be worried that the surround would become too focused. Between 4 speakers on the wall and four in the ceiling you'd be hard pressed to locate a singe speaker from the MLP. Actually none of the surrounds point straight at the MLP- that's kind of the point. You don't want to be able to pick out individual drivers.

Disclaimer: the only true Atmos tracks I have are the demo material. I'm not interested in any if the current releases with Atmos. But the Dolby up mixer is great. Watched plenty of action films and I've had plenty of jets and helicopters buzz in from overhead.

I'd say try them flat. If you feel like it's lacking then you could engineer up something to tilt them. I think it's a waste of time based on my results. Axiom, with their CNC machines could whip up a ring/wedge for tilting purposes fairly easy I imagine. Might have to rework the mounting brackets a bit.