puredrifting
Major Contributor
I don't know if there are any differences in the mount on a 100 vs. a 300, but I don't know anyone using a support on the 70-200/2.8 on a C300, myself included.
Most of the C300 MKII users I have seen in LA ARE using a lens support with the 70-200 2.8. I was on a shoot late last year with six other crews at one big event, everyone using that lens had a lens support. I agree, with operating, probably not needed. Once again, it's not the operating, it's the transporting your camera around a shoot. Run, slip, trip or stumble and subject that lens to the right G-forces and you could rip the mount off of the camera or at least crack or damage the camera body where it surrounds the mount. Not mention throw off your back focus. Cheap insurance.