How can changing roll film be faster than loading a Leica M7?
My M6 loads very quickly and easily: I even timed it once for another thread here, it was hardly any slower than most other classic 35mm cameras (I have no "quick-load" types, though).
Some people find it impossible to walk and load a M4 (to M7) camera, the baseplate or camera are too easy to drop, it is like juggling some people can do it, some cant. If you miss a kerb or similar, while you are walking nose, baseplate and camera may be damaged, etc. Loosing situation awareness is a risk in a crowd.
The late Canons e.g. VI to P to 7 series are easier the hinge back is not going to detach, and although the film end needs to be pushed into a slot, the remaining operations can be done blind (by feel) and allow walking. It is not quick loading like e.g. a Canonet f/1.7 QL.
Black or chrome does not seem to make a difference, when you are walking towards people, some are cautious about anything in your hand, so they will 'clock' any camera, they wont necessarily assume you are planning on photography.
If they and you are stationary, they will ignore you in general except for the curious.
Noel