Hi Eddie -
After spending a dozen years chasing steel in the northwest, I came back to striper country and found that there is a definite niche for the two-handed rod out here.
When steelheading, the use of a single-hander cut the effective fishing area dramatically verses the Spey rod due to worry about backcasting room and also time wasted between casts over the course of a season. Not to mention incredible line control for down and across applications (salmon / steelhead). I think people generally agree on that.
When striper fishing in the surf, there is a definite application of the benefits of two-handed casting as well as the giant flies that work so well out here. The most common misconception is SPey casting verses overhand, something that Europeans know a lot about. Some nordic countries specialize in two-handed overhand casting while the british isles use of long rods was for Spey casting. Anyway, my contention in this is that (a) it's much easier to fish all day in rumbling surf conditions with a two-handed rod (b) casts bigger flies easier (c) takes less out of the shoulder (d) easier to fight big fish (e) casts bigger line weights easily. For instance, the modified Sage 8wt European two-hander casts a 12 wt intermediate without difficulty.
I agree too, the two-hander has taught me a lot of stuff for fishing the single hander... like starting new casts with a mini-spey cast or using the singlehanded spey cast verses a sloppy roll cast, even the single haul spey cast that shoots line!
So when are you visiting us here in the Northeast?