Fast rangefinder lenses can be almost useless unless you have an EVF of some sort
For years I was one of those people who lusted after an f0.95 lens. Indeed fast rangefinder lenses are very worth it for many people. But believe it or not, they can be significantly more difficult to work with at times. Rangefinders for example need to be able to focus a lens like that. But in order for that to happen, the mechanism needs to be larger in order to achieve accuracy. It’s only in recent years that EVFs have come around good enough to aid in focusing with these lenses.
Now for the record, I’m referencing full frame sensors and rangefinder cameras using 35mm film with good viewfinders. The Leica M3, M4-P and M6 in addition to the Voigtlander Bessa series have great, bright, accurate rangefinders. But even so, focusing very shallow lenses is still difficult to do even for autofocus algorithms. The area that is in focus at shallow apertures is quite narrow.
Sony has a feature in their cameras called focus peaking, which at the full frame level is more or less useless, but with APS-C works fine. Voigtlander lenses designed for Micro Four Thirds with an f0.95 aperture work very well due to the more narrow depth of field per aperture vs full frame renderings.
If you’re using a film rangefinder or digital rangefinder, you’re probably working with a lens stopped down and you’re using the zone focusing scale. A rangefinder can give you very accurate focusing, but it’s very difficult to do. Even with an EVF, it’s pretty difficult to do.
So essentially you’re paying for a fast lens with a very shallow depth of field that you may not be able to accurately focus unless you’re very careful. The moral of the story: don’t get fooled and roped into the bokeh monster.