I fish with a 2 hander from my Kayak alot. I can't take sitting in them for too many hours unless I'm amongst heavily feeding fish.
I like casting with it, seems to be alittle less effort to get longer distance casts. Line management is a challenge at times..
I can use the standard rod holders with it which is a nice plus. Allows you to troll while your paddling from one spot to another. It also has a real fighting butt for big fish so my wrist doesn't get too strained.
It is alittle more of a challenge getting fish close to the boat at times, But I have a pretty good technique if the fish isn't too big.
I don't have a 12wt for comparision, But I heard the same thing about heavy weight rods too. That they don't cast as well But provide more backbone for lifting. I imagine getting the right grain weight and taper configuration makes a big difference with any rod.