Yeah they are great fly rods. i own two, an S4 and an A3, both are great.

I don't know what you man by "heavy duty" Kramsdell, but a 6 or 7wt can get lots of use on trout rivers, and other fisheries as well. I use my 7wt a lot for throwing big streamers. The line wt. carries out the bigger streamer fly much better. You want to relate to the action of a rod as well as the line wt. that it is suggested it should cast. All major rod makers make slower action rods, and faster action rods. Slower action rods can be harder to cast, but the feel of casting them is preferred by some...more like bamboo. Faster action rods take a more aggressive casting action with your casting arm to bend the rod, but can throw big flies nicely, and handle wind somewhat better. Med. Fast action, to me, are the biggest seller, and combine the best of casting, and playing a fish. There is enough bend/give in the rod to protect your tippet from breaking...better than a fast action rod anyway.