I have a 250EXC (2 stroke) and a 450EXC, both 2005’s.
The 450 is the best dual sport bike in the world and does pretty well in the tighter terrain. However, it is very top heavy compared to the 250 and is much faster. It’s a brute, IMO. That said, there is nothing like it if you are riding open terrain and/or hills. Gimme some sandy quad width stuff and I am all smiles on the 450.
If I plan to ride tighter trail and ride hard/fast, the 450 stays home as the 250 handles much better, is much lighter, and has a much friendlier power delivery. Mine is completely stock as I like the soft low end for real tight trail. If I had to own just one bike, I guess it would be a 250 2-stroke.
I never cared for the 300 2 stroke.....a little too much motor for tight trail. I think the 250 is the "baby bear bike" in the KTM line up.