It does not matter what receiver you have but you do not need speakers in your ceiling to hear things above you 5.1 is capable of producing that without having extra speakers it's really all down to speaker placement and nothing more. I've always looked at Atmos as a pinpointing system in that you have those extra speakers to direct certain sounds to them. I also look at it as defeating the object of what your receiver is capable of doing in the first place without them. Atmos uses metadata it's not a channel and neither is it discreet, it's a very similar environmental effect to what Creative Labs created years ago with EAX for games.
Regarding Dolby, many of the things they have done over the years are not exactly what I would call the bee's knees. Take Dolby Digital for example the weakest form of surround sound a format that many top engineers today refuse to use anymore. At the end of the day if you are happy with your system that is all that really matters. I'm not saying I dislike Atmos but from what I've heard of it on a few systems now it does not impress me enough to make me want to change my receiver or go out and buy more speakers. I prefer to let my receiver show me what it's capable of doing and that impresses me a damn sight more than Atmos will ever do in my book.