I have a 4/5 weight Beulah Switch Rod and a 7/8 weight TFO switch. I've been using the 4/5 a lot this year trying to get the hang of it, and I enjoy it a lot. I'm about to the point where its no more or less tiring to fish than my one handed rods, but I also end up casting it one handed a lot when I get frustrated.
The 7/8 weight rod has some definite advantages over my 10 foot 7 weight single handed rod. I stilld on't have the knack of really casting far, but being able to hold the rod with both hands takes a serious load off my shoulder and back. After a day of fishing with the 10 foot 7, especially nymphing, I was beat! The two hander helps that out.