One of the first things I learned growing up was that three wheels off road is a terrible idea. Let's see if Yamaha can change that.
I may have rolled a Honda CT-90 or two on myself as a kid, and the day I spent taking apart a URAL after Wes Siler broke himself in the middle of nowhere so we could bring it back in pieces was one of the longest days of my life. To be fair, three wheels in general tends to be a bad idea, regardless of the surface you're riding on.
At INTERMOT, Yamaha released the "01GEN" concept, a trike meant for both off-road and on-road applications. The "01GEN" acts similar to bikes like the Piaggio MP3, which actually perform a lot better and feel a whole lot more like a motorcycle than you might expect. The Yamaha obviously has larger wheels and more suspension travel, which will help it when asked to do off-road duty.