Hi Justice League,
So...you are a bluegill fisherman, huh? And the problem you're having is that when throwing larger, heavier flies your arms get tired and your casting stroke keeps blowing up?
Well, since you are asking for advice: If you've been catching fish pretty steady when using smaller-size flies, and if your casting stroke works pretty good when using smaller flies, and you don't suffer arm fatigue when using 3 or 4-wt. rods with smaller flies...then go back to using your smaller flies!
Maybe every now and then, say, 15 minutes each trip, tie on one of the heavier fly and cast it a while. Just play around with it for a few minutes as an experiment, but don't commit yourself to enduring an all-day ordeal of throwing a heavier fly. This way you keep having fun by catching lots of fish (on smaller flies) while GRADUALLY learning at your own speed the different feel and mechanics of throwing heavier stuff.
Joe
"Better small than not at all."