the shorter rod will probably be more fexible (but not necessarily), the question is really about how flexible the rod is, as opposed to using a rod that is stiff, regardless of the length of the rod. A shorter rod is normally prescribed for conditions you find in small streams, with lots of brush and trees on the banks, and gives you better control of your casts. A shorter rod that is very flexible generally is going to be best for close in precision casts, assuming it is balanced with a fly line and appropriate leader to turn over the fly as pointed out by Jackster. Although I spend a lot of time searching out steelhead and salmon, the challenge of hunting fish in secluded small freestone streams requiring precise casts with light equipment has always been one of my favorites. Sometimes the key will be to re-position yourself to enable you to make the cast with the equipment that you have. On occassion, that might mean moving to take advantage of a hole in the canopy of trees overhead to allow you to backcast up through the hole then straighten out the forward cast to deliver your fly. Lots of fun.