I'm glad to see you're perfecting UDS diffuser technology. I just had another idea to achieve more even temperatures. It is turbulence.
Your diffuser probably causes some turbulence but I was thinking about inducing turbulence mechanically with a small blower about half way down. Something like this maybe.
Dr. Mark (STL)
Ph.D. (honorary) Bovine $hitology
A thin line separates paranoia from an acute understanding of reality.