For the fronts...
[Link: speakercraft.com]I've heard them in a demo room that had those annoying stippled ceiling tiles found in older office buildings and they did a surprisingly good job - mated to Speakercraft in-wall LCR's. The beauty was you could get one grill to cover both the front and ATMOS speakers.
I believe up-firing modules got a bad name by the little junkers from the likes of Onkyo... the larger Klipsch / Elac seem to go a lot better. But as with all up-firing versions, you'll want a flat ceiling for it to work well.
Of course the prefered DTS:X configuration seems to consist of traditional front height speakers... and it plays pretty nicely with ATMOS content to my ears.