I think you'll be very happy with the 690 (if you can find one) if your looking for a mainly off road machine while taking pavement to get there. I got my 990 thinking it was going to whip around like a dirt bike off road but man-o-man, it is a big beast. Now, there are plenty of folks who can do that stuff with the 990 and it is very capable but you have to be a very talented rider. For me the 990 is a perfect bike because while I enjoy off road riding it's my daily rider and touring bike, I can load it up with gear for a week and be plenty happy without feeling like I needed to cut weight by leaving things behind. The Tiger is a good bike but it will handle much the same way off road as the 990, if you just want to have a blast in the dirt get the 690 or 525 exc.
BUT, the 990 will have more power, 21" wheel up front, better suspension than the Tiger... if you have to REALLY want a 990 Baja why keep the Tiger?
2010 KTM 990 Adventure
1978 Harley FX cut down