it also depends on the spot you are fishing, if there are nice long stretches of river around then the light 6lb will work fine if you have the drag set right and a long rod. But if there are obstructions around causing you to horse the fish every now and then heavier leader is beneficial. I was fishing around some fallen trees yesterday and after breaking off my first two I ended up attaching to my 10lb mainline and broke off two more lol. It was just heartbreaking when they would go for a hard sudden run right behind a big tree and then I would just hear a loud SNAP and the fish was gone. At some points I would hold my pin so that no line could come out to turn the fish around, I was able to do that with both my 8lb fluro leader and with the 10lb straight mainline setups. It was odd, for fresh fish they seemed to be very cooperative at some points...until they decided they were going a certain direction no matter what.