I'm the OP, I ended up going with the T63's. My riding is 60% dirt and they worked just fine. The knobs are spaced far apart and I thought they'd be noisy and vibrate some but they were smooth and quite. I wish I had the milage numbers with me but I don't. I'm guessing I'll have about 4,000 on them when they get replaced. Good tire, no complaints. My next set will be the Pirelli MT43's. I heard great things about them and mounted a set on my Beta trials bike just to try them out. So far I'm pleased with them and I can see no reason not to put them on the WR.
2010 BMW R1200GS, 2010 Ducati Monster 1100S, 2011 WR250R, 1985 Beta TR32, 1968 BSA 441 Victor Special