First, I don't ride dirt bikes primarilly, so some experts out there might say I'm totally wrong, and I'll be ill equipped to disagree.
That aside, I'd suggest finding a YZ-250. If you want a dirt bike that's great, speedy, and forgiving all in one package, the YZ-250 has these traits. Better yet, it's probably the most ubiquitous modern dirt bike (eg, from the 70s forward) so getting parts for it should be simple and cheap. If you go with the bike you listed, you might have trouble finding people who know how to work on it or find parts for it.
The YZ-250 is available in all price ranges, and it's a great fun 2 stroke to ride in the dirt.