About halfway through reset 5. Phase 2 is better; I got about 5k trophies out of E-7, and 6.9k as the best of 3 runs on E-8. Over 10K for the 80 stamina bonus stage.
Given that they added the extra 4 stages late, I wouldn't expect something unique like equipment. If its all non-unique stuff like bloom dragons/manyus/ampies/life crystals, I just see it as at that point I'm free to pick among various ways to spend my stamina based on how efficiently it gives the things I want, and if I don't clear oh well, not missing anything I can't pick up later.