My SQ-A brutally slaps compared to P6 or M645 1000s or RB67. That matters only for 1/30 and below for 80mm and longer focal lengths. when mirror is locked up I really haven't fell any sort of vibration with lens shutter.
I didn't quite understand the OP but if he seems to have the same problem with all lenses he owns then perhaps it's time to switch to Hassleblad.