i have and had several MF cameras, the only issue i had was with pentax 6x7 @ 1/30 and 1/60, but not by the level of what is described online.
i find most cameras quite balanced, even Kiev 60, pentacon six being quite quiet and balanced, mamiya rb is also quite good for it´s size and hasselblad very good indeed (hasselblad seems it creates a air cushion between the mirror and the GG)
Mamiya rb is just a pain to carry and is much better over a tripod, mostly like fuji 6x8 slr (to a higher degree).
One camera i really was not fond was fuji 6x7/6x9 rangefinder, the shutter was a bit violent even being a leaf shutter, another was mamiya 645 pro tl i bought new in 1998, the mirror slap was very intense, although it was a balanced camera.
i sold all mamiya rb and 645, also i sold the fuji 67 and i favoured hasselblad cameras and lenses... after i kept on buying things and got a bronica gs sistem and some pentacon/kiev stuff, also... a mamiya press camera that has some very very good lenses (the 100 2.8, the 75mm and the 50mm are among my favourite lenses, although the camera weights a ton)
weight for weight i think i would go for a chamonix or a shen hao over a mamiya rb, but that´s just me