Dmr are pretty good. I e-mailed saying could i buy a replacement spring for the tensioner, they just sent me a new one f.o.c. Best way to find out these things is to contact the company and ask :D
I changed from an avid ultimate V to the new hope trials disc brake. Loved it. So much better than a V. More powerfull, more modulation. I didn't have any trouble with fade. The only disc I've used that I would consider using on the rear.