I would look for michelins X-series or goodyear directional tires before I went with the bar tread NDT's - the few I have seen did not have much room to regroove them (cords are kinda close to the voids of the tread) 1100r20 and bigger
The larger sizes may be better (thicker tread and sidewall) but they would take alot of work to make it happen - at 50$ a tire I will stick with the michelin XL's got... (1600r20's!)
HTH
Matt