Switching to half-step + granny--must I replace my derailers?
I just went on a tour, and was unsatisfied with the 26-36-46 x 11-34 gearing, so I'm considering going to 24-48-52 x 14-32 (7-speed). Unfortunately, this calls for a rear derailer capacity of 46, and my RD-M760 is only rated to 45. OTOH, Sheldon Brown says derailer capacities are rated conservatively, and as long as I don't go into a crazy cross gear, I should be fine. Can I go ahead? If not, are there derailers with 46-tooth capacities?
Also, my front derailer is an FD-4503, which is a triple, and I hear half-step + granny works best with a double FD. How much trouble will I have if I don't switch? If I need to switch, do I need to spend a bunch of money or can I get something cheap?