This was a Off road trip with my friend. and our KTM's.
no backup car or anything else, just pure off road fun and camping. the longest distance we have covered from gas station to gas station was 560km. The KTM 950 Adventure had a battery cable and coming loose and a damaged Ignition Lock (sand). The 640 Adventure had a broken sub frame, and the same issue with the ignition lock and battery cable. No flat tires at all, never run out of fuel. Gps did work very well and my self made Garmin map was much better then expected. In sand we agreed that the 950 works better because of the extra power, yes even in dunes. In windy mountain roads the 640 Adventure would be the better choice. Fuel range on the 640 is a clear advantage. A steering damper on the 950 is highly recommended when going off road and especially on sand with deep tracks.