Used to do the 8wt rods and lines for the big, wind resistant, ugly, deerhair bugs. Even then I felt underpowered. Started playing around with heavier lines on my lighter rods and presto. With a big wind resistant bug you need the heavier mass of the heavier line to pull it though the air, not the heavy rod.

Now I use 7 and 10 weight lines but three and six weight rods, for the largest flies. Still use lighter lines with the lighter flies. I am not concerned about rod backbone because all you have to do is point your rod at the fish palm the reel or not give the fish any line and that fish is going nowhere, unless you snap your leader or bend your hooks out.

My eight weight rarely ever comes out any more, it used to be pretty pathetic landing a sunfish on an eight weight.