The question of rubber arose the other week when the new Nikon D4s was shown here at the shop. The Nikon representative took all of the staff into her confidence about the new features of the camera. The more arcane aspects of predictive double back bounce around tracking focus were a mystery to me - other than realising that the camera makes pictures in focus in spite of the user - but I did fasten upon one new aspect; Nikon have changed the rubber composition for the grips on this new camera.
Not before time. I use the Nikon D300 and D300s and love them for the images they take and the ease of use that they exhibit...but I hate the grips.
Oh, they are comfortably-shaped and soft and squishy, but that is because they apparently contain a large proportion of silicon in the rubber. They are fastened to the body panels of the camera with double sided sticky tape and while the tape takes to the body it eventually peels off the grips. They flap open under your hand. I've had the D300 ones reset by Ernest but my sweaty fingers will undo them again the the future.
Joy of Joys, Nikon changed the formulation of the rubber for their new flagship camera. A little less squishy and a lot more likely to stick onto the camera for the foreseeable future. Good boys.
Note: the big Canon cameras don't do this, but their grips are a little harder and thinner. Leica has opted for a bare metal body on their new T, though you can cover it with a clip-on plastic surface case. Fuji, Panasonic, and Olympus seem to be able to stay together pretty well.
Now whether they various manufacturers have opted for well-shaped grips or not is another matter - and the subject of another blog...