Dear Paul Ron,
The Mamiya RB67 (all models) use a centrifugal governor that mechanically limits the speed of the mirror while it's raising. It is not a myth. I've serviced my RB67 myself and i've seen the magical mirror governor in action. It is also mentioned in the user manual and service manual.
This reduces mirror shock greatly. I can confidently shoot at 1/15th with the RB, i even have some prints that were at 1/8 that came out just fine.
im no talking about mirror shock, im reminding the user to avoid blur when hand holding by not moving too soon after firing the camera.
i




