Circus Maximus....holy cow, this is exactly what I'm after!
I didn't suggest CM, but I had a feeling that was what you're looking for. That being said... DGM. I thought Circus Maximus "Loved Ones" was maybe the best "rock" song I'd ever heard. DGM "The Secret" (pt. 1 & 2) is one of the most awesomest tracks I've ever heard.
I think you need to hear more songs mate.
I think that Between the Buried and Me does that fast prog metal style with a lot of tempo changes better than DT but they do have growls. You could always check out their album Coma Ecliptic which is minimum harsh vocals though (like 90% clean vocals?) it's a fun ride.
90% clean vocals? Not even close.
Nope, below 50% for sure.
Redemption would be my first recommendation. I've discovered them last year through this forum and they are in my Top 3 bands right now.
Need is another great prog band. I really like their last album Hegaiamas
Daydream XI might also fit your bill
Not really prog but instrumental bands like Animals as Leaders and Scale the Summit do have the crazy instrumental stuff.
Did anyone mention LTE?