For a sense of what the bike can do, see the video:
Note that this uncorked KLX 250s has no problem reeling in or dropping comparable four-stroke bikes (including the lightweight yamaha 250 and 225 of my riding partners here) and even out climb 2-stroke dirtbikes on a steep, rooted trail (see video).
Recently rode the Shennadoah 500 with friends on a KLX 450 and XR650L and this 250S had no problem keeping up, even when they tried to drop me on the straights. But I could drop them easily in technical sections.
Pick the right gear, lines, technique, and position and this thing will keep up with or outperform far faster/stronger bikes.