I completely agree with Michael.
While your back is on the camera, it is safe. Removing or replacing the back is the most risky part of owning it, so do it as little as possible. I have only the one back, and it gets used on three Hasselblad bodies, so I do have to swap it around quite often. When I do, I like to mount the camera on a tripod, so that I can use two hands to remove the back very carefully. It only takes one slip, and the cover glass is scratched.
John