Pm'd....
I know you've teased the ultra tower idea for a while. As you know, I'm a tower guy. And while that is still true, I agree with your statements about X amount for BS or tower will get you better BS by way of materials. IMO that's why you just save longer. Taking money out of the equation, towers are better. More/bigger/higher sensitivity etc. Kinda like how two subs can measure the same, but deliver a different experience. My usage is 90% HT, 90% music so I might look at it differently than you. You are more music-centric, so if I were in your shoes, I'd call Ed Mullen, and have a talk. Test drive the ultra towers with a 3 or 2 channel amp and sit back and stroke my beard(metaphorical) in deep contemplation of keeping them.
Or!!! Keep the UBS's and do an atmos install with some prime elevation speakers using the new ceiling mounts. FTW!!!
Again, sorry for the hit n run, but life is a roller coaster right now.