When I did preload they had a conveyor belt in the middle. If you were in the front or middle, you'll never be able to catch and scan all your packages as it would just pile up at the back and mess up who ever was working at the back end. It was pretty damn awful.
The ones with the metal slides is probably easier because at least they go to you and stay there.
The ones with the metal slides is probably easier because at least they go to you and stay there.