My experience is 12,000 k thru Africa with a KLR650. Just returned. Mixed 40 degrees and sand thru the desert, with stormy days in the mud and pleasant driving in paved roads. My experience with the bike is very good. No mechanical problems at all, only one flat tyre.
During those 9 weeks I did not need to do nothing to the bike, only some oil once in a while. The water-refrigerator system worked very well, under difficult conditions (heat, load, etc).
A bit of a problem is the tank, only 14 liters. With no wind, quite a big load of luggage, straight road at 120K/h, I could do some 250 k. With wind, 180.
I still love the bike.