Speaking of MF rangefinders, Ive got a Koni Omega Rapid which I haven't used for a while. These cameras were made during the 60s and 70s and shoot 6 x 7cm film. All mechanical. They were intended primarily for press photography but they got the timing wrong - by around that time, 35mm started to be the norm for newspapers etc. Apparently, they did become very popular with wedding photographers and also aerial photography from planes.
Mine had this really weird issue with cable releases. The camera would only accept very sturdy cable releases and many of those would work perfectly fine for about a week. After a week, they wouldn't always fire the shutter - it was just down to luck whether they would or not.
I remember walking uphill before sunrise to shoot a landscape. I was carrying the Koni and a bulky tripod. When the first light appeared on the hills, it was really soft and appealing. I depressed the cable release and nothing happened. I tried again - nothing. I tried repeatedly and the cable release refused to trip the shutter. Eventually, it did fire but by that time, it was too late. The light had lost it's softness. Talk about unreliability.
I believe at one point, I did manage to obtain a cable release that worked all the time but I may have lost that one later.