^^ Learning is great!
But its going to take more then just a couple sliders scratched by dogs and video’s to figure it out (a lot more.) It’s more hands on.
(but Im sure you can get a grip on the process) 
“Probably should go the hardwater stain/shower door restoration route first?”…yup!
learn,learn,learn as you said.
Hey pro window cleaning and wcs you guys just helped me out on a customer an guided me the right way to go about it. Thanks champs “this is pro windows and steve from wcs” to my kids👍
jimmyswcs
Its not too great on shower doors from my experience. Im going to try to pick up some mr hardwater gear for it, and maybe some pure cerium oxide. I havent looked at the cheaper kit to compare it to the full kit so I’m not too sure what its missing.
Its not too hard. You need to learn to keep an eye on the temperature of the glass so it doesnt heat up too much and crack. Its much more difficult to do scratches at the side of the frame then it is in the middle. It definately takes practice to learn to step out the damage, pre polish is the most important step and then polishing just takes time. Hit me up any time you want to talk about it
I have used my Glass Renue System for everything from etched shower doors to dog-scratched patio doors to welding slag. It will do it all. It most definitely has a steep learning curve, and you will not be able to use it competently right out of the box without hours of practice, but it works, even on match head sized welding slag
With this kit you will not have access to the red glass renu grinding pads that are use for deep scratches.
