If your riding is truly technical you'll end up on a trials tire in the rear. Knobbies wear out fast and don't hook up. I'm tellin' you man. Looks aren't everything. Knobbies seem more aggressive but they only hook up in loamy dirt.. Something we aren't blessed with here in Colorado. Not our trails at least.
My last post where I said I switch to a dirt oriented knobby was strictly for the front end. Like I said, I'll never go back to a knobby in the rear, ever. Unless I move to the Pacific Northwest where it's usable.
The only discrepancy being that if I ride in the snow or mud (which is rare) I'd switch to a knobby in the rear. That's the only thing a trials tire doesn't do well in, because it doesn't clean itself out well.
Run a tublliss set up or HDD tubes and 6PSI in a trials tire out back and you'll be hard pressed to get it to break loose unless you're in the graveled granite. Then again nothing hooks up in that stuff, it's all about maintaining speed. Which a trials tire does well too, because of it's massive sidewall.
I'm just trying to save you some money in the long run. You'll replace knobbies 3 times more frequently. The 43 is money here in Colorado. Shoot over to the ADVRider forum and bounce around with searches for that tire in the Rocky Mountain regional forum. People swear by it. Plus, if you do any tarmac at all pretty much one trip is all you'll need to completely ruin a knobby completely and round off the knobs.
The DOT approved knobbies are so much harder of a rubber compound to combat the heat that road riding generates that they'll never do well in the dirt, they just won't.
I've been around the tire block... Spent thousands of dollars on tires for my dirt bikes. I'm just letting you know what works.