If you search around the various forums you will find quite a few people saying "I had a slider and never or rarely ever needed to use it". And then you will also find a few honest folks who will admit to either not having the slider or not using it, and then popping out the back window of their TV or worse. With a 2011 F250 short bed I first had a Reese Manual Slider, which I did use almost every time I went to back into a spot. Using it was not an easy evolution - getting out of the truck, moving the handle, getting back in, holding the trailer brakes down, pulling forward (and it didn't always move easily, and it almost always refused to move when I was at any sort of an angle). Did I have to use it every time I did? Don't know - what I do know is I never hit the truck because I always used it. Also even when pulling forward and going around tight corners I and my wife watched the camper coming close to the truck more than we watched the road in front of us.
Might have just been a worry wort, but when I switched to a Pullrite Super Glide I know that my towing/backing experience went from a constant worry to no worry at all. Yes the hitch costs more, and yes it is heavier and harder to handle than some of the others. But best hands-down hitch hardware I have ever seen or used. And provided the ability to tow forward or back into a spot worrying more about what was in front of me or behind me rather than where the camper was in relation to the truck. Having done this for a while I've learned that taking the tow/park experience out of the overall experience (i.e. making it as easy and safe as possible) lets you focus on what you really want to focus, the camping!
With a short bed truck regardless of the coach brand claims on angle (there are a ton of variables that go into that by the way, if you want to research - not all hitch/truck/camper angle possibilities are equal) I would have a slider, and an automatic one at that. A few hundred dollars are worth the peace of mind. At least for me it was. I have a long bed truck now and ended up selling my Pullrite (it kept its value VERY well by the way), but if I went back to a short bed that is the only way I would go.
Good luck on your decision. I'm sure there will be several more opinions show up. That is the great thing about this forum - lots of people will share and help you make a decision by sharing their own experience/mistakes/triumphs.
Merry Christmas!