I am running a DA triple and do a lot of hills. The big ones in this area run up to 12%, with most in the 5 to 8% range. The DA chain rings are 53/39/30 and my rear is 11/23.
Only once have I wished for a 12/25 and that was on a sustained 18% climb in the Sierras. The 53/39 combination keeps me riding in the gears I was used to when I had a double. The 30 (chainring) is a great bailout and gives me 3 lower gears than my double did.
My 50 year old knees appreciate this set up.