Hate to redredge the short v long rod debate but there was something I wanted to mention. In order to accurately compare fighting ability you have to compare rods of similar stiffness. There's no question a full size spey rod is going to be able to whip a fish faster than a 6' 3wt single hander for example. You're talking about a rod designed to cast 600gr of fly line long distance vs 100gr very short distance. The stiffness difference is simply too great for the shorter rod advantage to overcome.
If you want to make an accurate comparison, compare a 6' 3wt vs 14' 3wt or more realistically (rods that are actually made) a 14' 9wt to say an 8.5' 12wt. The long rod has some advantages, being able to keep the line off rocks, etc but in terms of sheer muscle on the fish (which is what turns them, tires them out quickly, etc), the shorter rod of comparable stiffness wins hands down.
I'm a big fan of double handed rods for a lot of reasons and of course I'm not going to take an 8.5' 12wt for my next steelhead trip because fish fighting ability isn't top priority. On the other hand I'm not taking a Spey rod for my next Tarpon trip either where fish fighting ability really is an issue.
