I would agree that it's better to HAVE it and NOT need it rather than to not have it and need it. I got myself into a tight spot once following my GPS and had an incredibly difficult time turning around and needed EVERY inch of my slider.
I'm not here to argue over whether or not you need a slider - I do. Questions is do I need an automatic slider like the Pullrite? I had one with my first truck and it was great, problem is that you CAN NOT back into the trailer unless you are nearly straight on. There have been times when I needed to back into the trailer at a greater angle than the Pullrite allows.
What I want to know is how much more difficult is having the manual slider and can you get one that allows a clean bed when the hitch is removed (like the Pullrite allows)?