I installed a Switch rod handle on my 9ft 5wt, I cut down a line to make my own custom grain Skagit head. 13ft Skagit, 10 foot of type 3, a cone head Zonker does 50 ft casts with 5 feet of back cast room. Great for throwing streamers for Trout. You can check out my rod build in another post, that includes details on what line I cut, etc. I'm also going to post my casting video on there.

Even without the switch handle I can single hand Spey cast this setup quite easily, the advantage is the ability to haul as you cast ( similar to a double haul) to speed up the line, but I find the biggest disadvantage is without a second handle is lifting, its harder to lift and and preform the snap of the snap T, that second handle just lets you really "flick" the line to get a nice layout before starting your peel.