I'm responding here because I feel your pain. I'm torn, too. But I need a DS, not a race bike. (My total solution would be a WR450R if Yamaha would ever make one.) Here are a few questions that I've asked myself:
Day rides of 100 miles? Mostly dirt roads and some single track? To me, that screams WRR. Most WRR fans get used to the power and adjust their riding style accordingly. You've had one. Can you do that?
If your are going KTM, I think you should look at the 350 EXC, not the 500. The 500 has monster torque and by the end of the day, can be tiring to ride. Pantah's son only needed the 500 to exceed 90 mph (target was 110 mph to be competitive as he explained in another thread) in a 1000-mile desert race. Americans get hooked on bigger is better. I've never believed that, and I still don't. (To be fair, the 500 is SOHC, and the 350 is DOHC, so valves on the 350 are a bit more complicated.) They weigh almost the same. The 500's outsell the 350's - maybe the 350's are more available? Read both the 350 and 500 threads on this site.
Yes, KTM's require less frequent maintenance if you are not racing. However, they are race engines with high hp/liter, and much more highly-stressed components. Regardless of how you ride, they require more TLC than the Yamaha. The biggest difference may actually be the suspension. Will you use the KTM's capabilities? KTM's are also lighter because they have weaker subframes and don't carry big alternators. Is that OK with you? If so, go for it.
Finally, you will also end up spending money to customize the KTM. You will (evenutally) put on a different seat, may want different or higher bars, handguards, larger tank, etc. Tires are a wear item on both bikes.
1990 Honda NT-650 Hawk-GT
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