I also was in love with 24mm when I shot SLRs for more than a decade. When I put together my rangefinder kit 15 years ago, the 24/25mm wasn't an option in Nikon RF, so I got a 28mm and a 21mm. Today, I'd get a CV 25mm.
I like separate finders for wide lenses. The view is much closer to what you'd get with an SLR image and focus isn't critical. But it is another piece of gear you have to worry about.
As a longtime 24mm user, I've never been completely happy with the coverage of 28mm in RF.
Slower speed is an issue. I've found that I end up using a fast 35mm f/1.8 when low light is critical and the 28mm or 21mm when there's a bit more light.
If I shot Leica Ms and was putting together a kit, I'd take a very hard look at the new Zeiss 25mm f/2.8. It focuses closer and is relatively affordable compared to the Leica alternative.
Nikon S2, S3, S3-2000, SP, SP-2005 / Kiev 2a
Biogon 21/4.5; CV 21/4; CV 25/4; CV 85/3.5; the following Nikkors: 2.8cm/3.5; 3.5cm/1.8 (1956 and 2005 versions); 5cm/1.4; 8.5cm/2; 10.5cm/2.5; 13.5cm/3.5
Soviet lenses: Orion 28/6; Jupiter-12 35/2.8; Helios-103 50/1.8; Jupiter-8 50/2