I haven't tried it, so I can't offer firsthand experience. Leica decided that the depth of field with f:4 at 90mm was within their acceptable spec for the combination of rangefinder baseline and viewfinder magnification in the CL, so that's the matching lens they offered.
If you can test your proposed combination to see if it will consistently match your standards with your personal ability to focus, required presentation (4"x6" machine print... slide projected to fill the side of a barn), etc, I'd recommend that. You can always stop down a faster 85-90mm lens to f:4 and "come within spec", but that's probably not why you want something faster.
Lee