John,
I do not know the answer to your question, but, a good rod building friend of mine and I were discussing rod building one day. We were talking about one fly rod I have that was rated as med/fast which I think leaned more toward medium and I said that maybe if we put double footed guides on it that might stiffen it up a bit and he told me that if you put double footed guides on it, it would make it slower which I found interesting.
With your permission, I will follow this thread and see what the experts here have to say about the weight difference between single and double footed guides. It should be interesting. Good question, by the way....
Warren
Fly fishing and fly tying are two things that I do, and when I am doing them, they are the only 2 things I think about. They clear my mind.