I've got a 450 EXC and have only been able to put about nine hours on it so far. I love the bike for it's handling and useable power, but I'm reserving judgement on it's dependability. I've had a leaky master cylinder, leaky cam chain tensioner and am questioning if my oil seal is allowing the oil from the tranny to migrate to the motor side?
Minor issues so far and they have been covered under warranty. The worst part is, it takes the dealer two to three weeks each time waiting for parts. I just had the valves reshimmed and again a two week wait. The bike has been in the shop, more than my garage.
I'm like you, I bought this as my trailbike, CO vacation bike and other rides where a plate is handy. I've got another bike to race. Have you had any of the other "issues" that seem to be all over the internet?