Thanks for your opinion but I'm in it now to get the best sound possible I feel I should be ok with my in ceiling setup
First, you are asking guys with years of real world experience for advice, and then calling their expertise 'an opinion'. It's not. That's incredibly rude and dismissive of not only their experience, but the facts that go along with it. Since you're a car guy, it would be like someone saying they want to only put speakers in the engine compartment and trunk, nothing IN the car. You tell them that wouldn't work, it would sound bad, and they 'thank you for your opinion'. It's clearly NOT an opinion, is the reality of the situation.
So, you CAN do all ceiling speakers, but go in knowing this isn't how you will ever get the 'best' sound. As a former Sonance dealer, I like their speakers, but I absolutely didn't find them to be worth the money spent on them and coming way down in price actually delivered very similar results. Spending a lot on in ceiling speakers is a good way to spend a lot of money, but not a great way to get incredible sound. Similar with other major brands. It's a pretty standard speaker, without a proper backbox, and pretty standard materials. What in the world makes it cost so much?
If I was looking for in-ceiling only, I would lean towards models with a built-in back box, and some significant directionality to get the audio pointed out towards the listeners. Something like these for the front three maybe...
3-way in-ceiling home theater speaker with built-in back-box
www.crutchfield.com
I might go smaller and more generic for the rear two speakers.
You can't bounce between a properly setup in-ceiling 5.1 system to a 5.1.4 system and repurpose the in ceilings for Atmos without pulling everything out, patching, and relocating everything. The locations for 5.1 surround and the .4 for Atmos is completely different.
This IS your choice, but it would be helpful to understand that while you can do this, that you won't be getting the same quality you could get with decent in-wall speakers or some decent bookshelf speakers in the room. Which is fine, but you need to be respectful of the information given, not dismissive.
I use in-ceiling speakers in several rooms for audio playback to improve upon the audio from my TV. I wouldn't say it's great audio, but the speakers are a massive improvement over the TV speakers, which was my goal. They also work well for background music when I'm listening and working around the home.
https://www.monoprice.com/product?p_id=34198
These worked well for my needs, and were a reasonable price point with solid quality.
Any room I had with a TV where I could manage in-wall speakers to go with a TV, these were my go-to speakers to massively improve upon the TV audio...
In-wall speakers allow you to expand your listening environment throughout your entire home, as well as removing the clutter of giant box speakers, giving you back your living sp
www.monoprice.com
I've used those speakers behind projection screens and in surround systems as well, with clients who were very happy as they didn't want any floor standing speakers at all.
All I can say for placement, is that I leaned towards getting the front speakers even spaced, and wide in the room for better imaging. Center channel was always on center. Surround speakers need to be properly placed in the room as well.
I always used at least 14 gauge cabling for all my work.