I have a Pull-Rite slider, but if I were to get another one today, I would have to look at the Demco Autoslide!
I am NOT saying that I would just run out and buy one, but would certainly read up on them before I decided on which one to get.
With the Pull-Rite you need an adapter plate for your pin box. Originally they had to have holes drilled in the pin box, with some having to be tap'ed. They now have a plate that locks over the pin, with two bolts holding the front of the plate, and works much easier. I had to be towed numerous times back when I had a 2003 F-350 6.0! Was a nuisance trying to pull the bolts and removing the plate..
Reading about the Demco in the May, 2014 Trailer Life, they have adjustable guides built into the hitch, so you do not have to modify your pin box in any way.
Sounds like a 100% improvement in the method of making the slide work to me!
Just my 2 sense..