A speaker with good dispersion certainly helps but the speaker often still needs to be aimed especially if following Atmos spec and multiple seats/ rows.
For example dolby specs the Atmos speakers be in front (and behind) of the listeners at 45 degees. Even with good dispersion speakers this should be aimed and few speaker do verywell at 45 degrees and all will still have some high frequency roll off. Even the Kef CI200RR starts to have a lot of roll off after 45 degrees. So when if I set it for 45 degrees for the front right seat how does it look for the middle seats or the front left, or the second row?
The new Triad rotating Silver speaker will solve a lot of problems but there are many ompanies that make angled speakers which angle 30 degrees or more and would be good for this type of application.
In a nutshell the shorter the ceiling the more immportant an angled speaker will be. Atmos is tough in most home to do well with tandard 8 foot ceilings. For one row of seating it can work well with angled speakers and toeing them in a little.