I appreciate the post. I've often wondered what the difference was between the different types of spey lines. The marketing material just doesn't seem to explain it clearly enough to differentiate.

I've been practicing single-handed spey with my regular trout rod for several years now, and I can empathize with your frustration. Although I can cast small floating flies fairly well this way, large sinking flies are still nearly impossible. Maybe I'm just asking too much of my equipment.