Buy a wr250f, get to wide ratio gear box,flywheel weight, lights,..lose the tank and seat and replace it with a thin(IMS) tank and new seat, Change the cam timing to match the yz, and snip the black wire(Rev limiter,I think).....
Or, buy the yz250F, and add the flywheel weight(IF it's needed), add battery powered light...
The better riders use a YZ in the woods. The gap from 1st to 2nd is better on the YZ. Most of us like the closer ratios and if 1st is too high, drop 1 or 2 teeth on the rear sprocket. I'm not convinced to the benefit of a flywheel weight yet although I would like to try one first. I noticed with the heavy studded Trelleborg(which would act similar to a weight), the bike lost snap out of turns... Don't think that we don't ride tight woods with the YZ because you would be wrong. These things work really well stock as long as you are a good rider and don't mind using the clutch. If you are into slow trail riding get the WR.