[onre]

Almost all old rangefinders were quiet, ditto for folders and TLRs - it wasn't in any way Leica specific. SLRs, on the other hand, can be rather noisy because of the mirror slap. Pentax 67 sounds almost like a weapon.

[KaiserPro]

I was watching an interview with a famous street photographer[who I can't remember], he was saying why he liked leicas,

one was the viewfinder position, and the other was the silent shutter (I've never used one so I can't comment)

The pentax 67 is a medium format monster, with a solenoid actuator. I have used it and its a wonderful beast.