I have a 2010 WR250R, and today I sat on a 2013 KTM 350 EXC-F.
50 pounds is a big difference. I'm tempted, but since I ride alone in the middle of nowhere, reliability is a huge factor for me, and I keep hearing people say that the KTM's, reliable as they are, can't hold a candle to the solid titanium bulletproof 250 motor on the Yamaha.
I ride slow, but tight single track with very little street. Money isn't really a factor, so we'll see. Maybe next year... :)