Gene,
It's obvious that you've never fought a fish on a two handed fly rod, as you are fixated on the wrong component of leverage. The important bit is not the lever arm from butt to effective tip, but from the butt to grip hand.
Here's an example. I've got a fairly good sized reel that I use for both single and double handed rods. Drag is set at ~7 pounds. Now, with a 13' rod, bent while fighting a fish, my effective lever arm is just under 9'. With a single handed 9' rod, effective lever arm length is about 6'.
With the single handed rod, the grip hand is about one foot up from the butt (which is placed on my torso). Double that for the two handed rod
Thus, the force at the grip hand needed to resist a fish with the single handed 9' rod is 6 feet * 7 lbs/1 foot or 42 pounds. Force needed for the double handed rod is 9 feet * 7 pounds /2 feet = 31.5 lbs. Add the fact that I get a huge advantage in being able to direct the force vector to the fish's disadvantage on top of the decrease in force needed, and the longer rod wins the contest every time.
This is assuming that the water you're fishing is compatible with the longer rod. I'd not be to likely to use a 13' rod on a stream 20 feet across. Though there was a Silver hen that was in the wrong place at the wrong time...
Now, given a fixed butt to grip hand measurement, as would be the case for boat rods, I'd give the nod to a shorter rod when it comes to doing winch duty.
Scott
