5.1 all in ceiling speakers

I have spent considerable time in the forums and at various websites (Dolby, THX, Crutchfield, etc.) gathering knowldege for an all in-ceiling 5.1 set up and before I cut holes in the ceiling I would like to get the community's opinion. All the speakers are the same, namely Polk TC60i. These speakers have 6.5" drivers so the sound should be somewhat diffuse compared to a larger speaker. Also, the TC60i's are angled by 15 degrees (entire speaker) so they don't point straight down. The tweeters are also aimable. The sub will likely be in a corner on the TV wall but is not shown in the diagram.

Thanks in advance for any and all comments!

Thanks for the reply to my OP. The goal is better than good enough, but given the physics of in ceiling speakers I have managed my expectations to somewhat less than great. The L C R will be aimed at the MLP via the aimable tweeter and by turning the whole speaker so that the driver (off set by 15 degrees from straight up/down) is also pointing towards the MLP.

Here is something I have not been able to figure out. The standard recommendation for normal standing speakers is to have all the speakers equidistant from the MLP, or in other words, on a circle. However, everything I have seen on the internet and the only article on in-ceiling speaker placement provided by Crutchfield (google "Crutchfield in ceiling placement") states that the L C R should be on a straight line. I would appreciate some insight into this. I can do either at this point (no holes in ceiling yet).

Thanks again.