Which reinforces the Pentax decision to advance body design to a MLU (Mirror Lock Up). Such practices abound with MF SLR designs that split the mirror so that half went up and half went down.... I can't recall but I think that might have been a Bronica???
Yes, the mirrors in MF SLR's are large and heavy and mirror slap is an issue.
One of the reasons I prefer the leaf shutter designs like the Fuji big rangefinders and Mamiya Press models. No mirror, no focal plane shutter going sideways or vertically, etc.
As might be expected, I certainly agree about using the Mamiya Press cameras. The in-lens shutters and shutter cable release in the holding handle, along with the mass of the camera, all contribute to slow speed hand-holdability. I don't recall what was the slowest speed I have ever used, but I think around 1/8 to 1/4 or so. Not the best, but a usable photo nonetheless. At higher speeds they are really good.
I used to know a guy who used the Pentax 67 as a wedding camera. He thought it quite good at that, and was successful as well.
As to holding the OM-1 securely, that would be good advice for any camera. Especially the smaller versions like the OMs. Fujica put a special mirrow dampener on their ST 901. I don't know if that idea carried over to the AZ-1 and the bayonet models or not.
When I was younger and taking a lot of photos, I could even hold my Yashica TL Super at 1/2 second in an emergency, but usually took 2 or 3 shots to be sure one was OK.
To me, that is one of the keys with any camera. Taking enough photos so that your muscles become welll trained (strong and steady) and you learn to control your breathing. I am sure most have seen good quality with almost any MF camera if the user was accustomed to using it, and careful. For that matter, how many good photos were obtained with 4x5 press cameras? It wasn't all the large negative.
Nice photos by all. Thanks, I enjoyed them. I feel inspired to crank out my Super Press 23 again. It has sat sadly neglected for too long due to a (now improving) back problem (the one down side of big MF).