I found the easiest way was to do both, so I also have a Suzuki DR650.
http://ozstoc.com/Smileys/default/hat1.gifThey're not quite a BMW 1200, but you can buy them cheap, ($3 -$5k will buy a good one) and they're more practical than all the bigger Dual Sports bikes when the going gets really tough. They do require a few mods, (bigger tank, better seat and some suspension work), but they are pretty much bullet proof. There's literally hundreds of aftermarket parts available for them, (see
www.procycle.com). It's also very easy to change the gearing to suit the ride. 1200cc's are good for Bitumen and Dirt Roads, but a real handful, (and a bit too pretty), for genuine trail riding.
I love my ST, but it's good to have the option to get into the dirt too. This way you get, (almost), the best of both worlds, without having to sacrifice your ST. It's worth a thought and it works for me.