20k miles is not a lot if it hasn't been revved to the moon and has had decent maintenance. I just sold an '06 950 SM with 32k. Valves still in spec. Uses no oil. I picked up an '07 990 with 30k, which I will be heading off to Alaska on after some basic maintenance.
Blue smoke is not normal. Jetting is not the easiest on these bikes, given the carb access. How does it run? Good reading in the HOW section. Don't be scared off by the talk of water pumps etc.
KTMs--300, 450, 990