The 650 is an attractive and versatile bike. But if you're looking to explore more technical trails, take a look at these:
For a light street legal bike that is also good for trail riding, try the Suzuki DR Z 400S:
http://www.suzukicycles.com/Product%...1/DRZ400S.aspx
For something even more serious with top notch components, try the KTM 450 EXC:
http://www.ktm.com/us/enduro/450-exc-usa.html
Dual sport riding is fun...it doesn't get the same relative attention in the US as in Europe and other countries.