Knowing Russell, I'd also say Maxxis.
If I was to ride that bike, I would fit Dunlop D606 all round.
Road legal and super capable offroad.
I dunno how I would feel about a little 2T like this, it uses quite a bit of juice, say 14km per liter if you dont rev it hard.
Add the cost of racing 2T oil , say an extra R25 per tank, and its quite expensive to run.
Also I change gearbox oil in mine every 2-3 rides, so every 10-15 hours. (it only has a .7L gearbox)
The KDX is quite tough and you could probably run it with the cheap 2T oil, and change gearbox oil every 5000km.