>>297474If you plan on doing much highway (more than a mile or two at 65+, or for commuting around town (50mpg, bitches!)) I wouldn't go any less than a 450. At higher elevations you'll want more.
It's not till I get up to 10k+ft that my 525 really starts to run like a dog.
Bikes have a steeper learning curve, but once you get past that they're far more fun than a kwad. Plus they're generally easier to get plates on, making them about the ultimate /out/vehicle. You can find used bikes for $3k-ish that'll serve you well for years if you maintain it.
I wanted a KTM from the get-go... Kickass bikes ready to go right out of the box, but they are pricey. I was looking at the WR450's till I found a smoking deal on my KTM 525, and it went home with me that day. Personally I'd rather have the power/engine and not twist the wrist as much, than be miserable riding and wishing I had more.
Don't forget to budget in gear/equipment too. Helmet, boots, gloves, pants, armor...