Who uses the hard coated bearings in bbc nai s and rods and what's pros vs cons

Unless your having sizing issues, there are no cons.

We have run these with no problems at all in out TD:

Rod: Clevite CB743HNK; Main: MS829HK1 [0.001” under]

All of our motors are coated bearings and narrowed including the stock motors. There is power in bearings and coatings. If you are not looking for every last bit don’t spend for it.