My son bought his first dual sport last spring with a new 350 EXC-F. He did a couple practice events and raced it in the Mexican 1000. He said he should have bought the 500 as top speed with the 350 was only mid 90's on the playa. He needed a little more speed. He claims he'll show up next spring with a 500.
I have a WRR. There is no comparison. The KTM is the real deal. The WRR is a nice dual sport and very practical, but it's not a KTM. The new KTMs are very high fit/finish these days. If you are going to race it, then yes it will have a lot of maintenance, but not like a motocrosser. If you are going to ride it as a play bike, I think it will give you a lot more playing than the Yamaha will.
No doubt, though. The new thumpers are expensive to rebuild no matter what brand it is.
Straight ahead and faster -Bo Weaver 1970
"There I was..." -Griffin Niner Three Hotel
"One day closer to a parade..." Jonny Gomes, spring training 2013