I really do enjoy the lighter wt rods on small water.
Trout on any small stream running nymphs or drys. Small mouth bass on the Umpqua or John Day is a blast!
On the Rogue, during the salmon fly hatch, I reach for the graphite for it's better backbone and quicker response.
I do use the heavier glass rods for other things, like running plugs for steelhead or twitching traditional flies for summer steelhead.
It's kind of like stepping into the woods with an iron sighted 30-30.... not always the best tool for the job, but sometimes it's perfect
