I get a lot of missed strikes with the extended body flies. I must not be tying them right.
The best pattern that I have found is the Flex Hex by John Nebel. The body folds up and collapses so even the smaller trout can take it in. It rear segment also flops into odd angles and if you have ever been in the middle of a Hex spinner fall, the mayflies are contorted into odd shapes.
The Flex hex - The Flex-HexThe fly that did the Limbata as told by Jim Hauer - Global FlyFisher