We ride a lot of similar stuff to what you are riding in. Roots, mud, hardpack, sand, creeks, snow, rocks.
I have a IRC on my new KDX, came with it. I am not happy with the wear on the unit at all. Traction seems good though.
What my friend and I changed over to is the Maxxis CT6001 tires. They are half price of any major name brands, like 30-40 dollars per axle. They kind of look like a paddle with tread cut in to it. I had that on the front and rear of the xr600 and they worked really well. The 600 is a hard bike to tell if the rear tire is better, but the front was for sure over the michellin there. My friend has just the rear Ct6001 and loves it. Wear is about normal, but at the price we can afford to change them twice as often as like a Dunlop tire.
We got them at RockyMountain MC. That was the cheapest place to pick them up at.