>>2709389Heavier weight, lower line speed, less sensitivity, slower action, and more reverberation
On a 5 weight rod if the extra weight of glass is an issue you're a pansy
Slower action and line speed doesnt matter inside 60 feet and actually gives more delicate presentations
Sensitivity isnt much of an issue in fly fishing I've found, you're either floating a dry fly (visual) nymphing (visual) or swinging/stripping streamers and wet flies where the take is seldom subtle.
Reverb is just the rod whipping back and forth after your stop and it's not a huge issue.
I'm biased in favor of glass, though, the majority of my fly rods are glass.