The local shops who work on KTM's have a steady string of older to newish KTM 4 strokes waiting to be rebuilt,its been like that ever since they came out. Some last a while,some do not. Rather these shops know how to rebuild one properly who knows? The 520's/525's/530's that last and last and run 40K miles or even 10K miles are the stuff of legend,only heard of them on the internet. Im happy some do but just never heard of one around here,most would be on their second engine by then,if not the third. A Honda 450/Kawi 450/Suzuki 450 is about the same thing,once they have a bunch of hours on them nobody wants them and the value plummets quickly. The Yamaha 450/250 seems to last the longest and has since they first started making them,not sure why.