Really? Most of the wheels sets I see for sale have crowned drive wheels and tracking wheels in the same set. Including those from Origin Blade. Seems odd that they would sell complete sets like that if it wasn't an acceptable setup.
As for the belt tension, it uses a 44lb compression spring inside the riser tube. To change belts you press down on the riser with the tracking wheel. Seems adequate but with this being my first grinder I don't have a feel for what the proper tension should be. The grinder is a very common design that many builders have used so its been battle tested by the knife making community.
As for the rigidity, the grinder is build from 2" and 1.5" tubing that's .25" wall thickness and fully welded to a 12x24" .25" steel plate. It's very heavy. I don't think flex is an issue. It feels like a tank.
I'll go back and read the sticky that was mentioned and see if I can learn anything. Maybe I'll get a laser out. Haha