Depends...
Depends...
Well, I have a CL, an R-D1 and now an M6-TTL. Some observations:
The CL (like the CLE) has the portability factor. The meter is pretty good, and it is easy to load. And since it's a light-tight box, for everyday shooting there really isn't much difference in good light.
The finder is small. I find myself really having a hard time doing any shooting in low light. I think the rangefinder base is pretty narrow, which means focusing at 50mm f/1.5 is about the best it will do. Also, I find the CL only focuses down to 3 feet, and my Voigtlander lenses (at least the 28mm Ultron and the 35 Pan II) focus a little closer, so you lose that part of the range.
The M6 has a larger baseline, meaning it will focus in lower light, make it more obvious when the focus is 'in', and will support more lens combinations without an external finder (i have the .72 finder, so I can shoot with 28, 35, 50, 75 and 90 lenses this way). If you were looking for shooting more narrow focal lengths, the .85 finder is better (I think it shows a 135mm frameline). The M6 supports focusing down to the minimums on my lenses. And it allows you to switch the framelines for previewing the framing of a shot. The meter is also not mechanical, so I think it will be less likely to fail with heavy use of the camera.
I like the framing on the M6 for the 35mm lens--most of the viewfinder area, and easily visible to me (I don't wear glasses). The M6 .72 finder's 28mm framelines are hard to see completely even for me, so I figure it's anything in the viewfinder and I'm good.
If you shoot a lot in low light, want an easier to use viewfinder, and don't mind a slightly larger camera, the M6 could be a good choice. If pocketability is your main concern, the CLE is perfect. Especially with that nice 40mm lens! It's a beaut and takes great pictures.
FWIW, compared to the others, the R-D1 is a great camera, albeit it is currently pretty darn expensive. It's main advantage is digital capture. Think of it as a Bessa with a digital back. Of the three, the rangefinder patch is the brightest, but it just doesn't pop into / out of focus like the M6 in lower light. I love shooting with it though, and it will still have a place in my bag since it's about the size of the M6.
Ken