So many benefits to a rim grind as opposed to a smooth. You can ride in the wet and still maintain your confidence, yeah maybe a smooth rim might hold you for a bit but the chances of it slipping are so much higher than with a grind.
Can ride in dodgy conditions (shipley glen rocks) where there is dirt etc, grind doesn't really get affected by it. Ask every competition rider who ride natural and see if they have a grind, I can guarantee unless they have dual disk, that they will have a grind.
Smooth rim just loses confidence imo.