My Dahon Cadenza has Alfine hub gears, Shimano mech disc brakes and Big Apple 26x1.9 tyres. I ride tracks and trails on the aluminium rigid fork. It is similar to the Bad Boy but with a better eccentric bottom bracket and a folding frame.
I think the MTB world has become too stratified with lots of different classes. What you need is a "mountain bike". UK brand Orange still make their P7 which is really versatile for this kind of mixed use. Cross country would be the best current style except they lack rack eyelets, so you will have to go for entry level "trial bikes".