I would never gat a KTM, I went to the dealer when I was looking for a 450 and the told me I would need to buy 2 of them. one for a race quad, and one for a parts quad. they have so many problems and if you break parts you cant buy OEM
I haven't heard of any.......at least no more than any of the other "450s". My buddies Outlaw 525 engine runs the same engine as the KTM and has had less issues than his brother's YFZ which was just rebuilt.
I couldn't care less about OEM.........I only buy aftermarket. I:I Engine parts are easy to come by since it's mostly compatible with the 505 and 525 bike engines as well.