I have 4 bouncers right now, and I already bought 4 more speakers; so I could get 2 more bouncers and be done with it, but my dad's gonna help me mount everything up high. I've been to a few home theaters in town where they're top-mounted, and it's night-and-day with my bouncy-house speakers.
I know people don't like Techno Dad here, but I think he made a good point about heights getting better imaging than tops because they're further apart and can fill the gaps easier than top that sit closer to you than your front and rear speakers.
I've made a decision now.
I'm going with 5 heights and 3 tops not because of Auro, but because of DTS:X (since it can use whatever):
I'll never have front wides in this room as they're in the way of getting to the couch, so I can go with 8 heights instead.
When I was at someone's home theater with a Storm, he had the "voice of god" speaker as well as center heights, front heights, and rear heights, and 6 tops. The center-top speaker actually played a role in my immersion, and I know DTS:X content can use it even if Atmos can't.
I want a center-height because IMAX uses it. While I only have a few videos with IMAX Enhanced and a few Auro3D demos, Neural:X can fill the gap, and I already have the extra speaker since they come in pairs.
In terms of wiring, I'm already running a wire past that position, so it's not going to change anything in my room. Same with the center-top. There will already be a wire going across the top from the left to the right speaker, so I can put a t-fitting and add a center drop no-problem.
With this 15-channel configuration, I don't have to choose between Auro3D-style and front wides since I won't have front wides.