It only takes me about 5 secs. (or less) to change a shell holder in either the round or square tray models. Speaking of which, I decided to convert one of my square tray models a la Ben, but with a slight difference. To wit, I used an Atlas razor saw to sever the tray from the body, i.e., the part which fits into the red handle. After removing the rod that prevents primer "issues," I reinserted the remaining fitting into the handle, but used masking tape (which I sometimes use to repair the "saddles" on my bikes)* to hold everything in place instead of JB Weld. I think this modification, with a nod to Ben, will eliminate many of the frustrations with the "as issued" device!.
*I believe the brand name is "Mystic Tape," which is a narrower, slightly heavier version of duct tape.