Interesting post....
I can see your point here Brian. I know some guys have picked up a little et by going to a double, but I think that is more because of changing from a worn out or cheap shock, to a better quality.
I have always felt that the more adjustment you can have in a car is better, as long as you are going to take the time to adjust, which a lot of guys dont, so then double adjustables would be a waste of money.
Another point of interest, a large number of pro mods are built using Santuff coil overs, at a substansially higher price than konis. They say they are a few hundreds quicker than the konis. They also are a double adjustable. But I have wondered how a small company like Santuff can make a better shock than koni