Just go off service history and condition. Oil changes should have been done to schedule. The DCT uses the same oil, it's not separate, and there are filters for the DCT which are replaced as part of regular servicing. If it's approaching 16k as mentioned above factor in the upcoming valve clearance check costs into the price. They are a little prone to pinprick paint issues on the frame, more noticeable on the white frame like mine, so that's an item to check for. The < 2020 models benefit hugely from suspension work especially at the rear. Otherwise just look for a tidy well maintained bike, they really aren't prone to any specific problems.