Yeah, I really liked the instrumentation in Movement 1; Ira made human-like dynamics out of a pretty linear MIDI. I also liked the one timbre that's basically just doubling stuff in Movement 2, but it's that chorus-y piano just to add some TeXTUrE.
Your tension/release idea made me look at Apocalypse in 9/8. I think its tension/release comes from the polyrhythms realigning every few measures, and the bass constantly being on B. The bass made me analyze a lot of the harmony as just being relative to Dominant, like v7/v and VII/v. Might try it some other time to see if it's what you meant.