Like many that belong to this site I have cut my teeth riding in the dirt. Motocross and Flat Track racing was my all time favorite, even though I wasn't very good I still enjoyed it. Back when I raced I could touch the ground on my bikes, today's bike with their superior travel keeps my feet far from coming close to the ground. Even a Sports Tourer bike like the Concours 14 is difficult to touch the ground for me. Being vertically challenged has its drawbacks in our sport which can eliminate some great machines. With that said and also hoping to be in the same position to add a dual purpose bike I'm leaning towards the V-Strom 650 with some aftermarket options, as was previously mentioned. For whats its worth last fall I talked at length with the owner of a successfull mail order company called Whitehorse Gear in Conway NH about the same thing. He told me he could drive what ever he wanted, and his stable consisted of a V-Strom 650 and the Suzuki 400 street legal dirt bike (not sure on the model) His knowledge and experience from talking to riders from all over gave him the pros and cons of just about everything available.
I have to agree with the knowledgable statements made in reference to the V-Strom. There is a good write up on the new model in Rider Magazine, I happened to find the test on the internet.
Very interesting topic, hope you find what you are looking for.
Good Luck