I have a Clutch drilled 90x4x65, and its awesome on the ths. Strong pin, with a smooth MB. Have to watch the surface on it, because oob, it was too much on the ths, but at 1000 with polish, it was not enough. I think I have to keep it at about 2000 with no polish.
I have had great success with balls with the MB in the track. Predator, Vortex Afterburner, Tomahawk, Stinger, Heat remake, and probably some more that I can't remember at the moment. All different pin lengths and angles to the val. For me, it allows me to stand closer to the friction, and not have it go crazygonuts off the dry.