I have cast the H2 and was really impressed. My comments here: Helios 2 vs Zenith
Didn't compare it to the original Helios so I can't tell you whether the upgrade would be worthwhile. If I were in your position and already had an 8' 6" 5 wt rod I loved, but wanted to get a new one, I would think about supplementing it rather than replacing it. Maybe a 9' 6 wt for distance, or a 7' 6" 3 or 4 wt for small streams.