Well, I am still a little unclear on what you are trying to do. Are you looking at a sliding track fitting in either a T-track or a miter slot? In the T-track, it is locked in. If you need that capability, it won't be available in a standard miter slot. As far as can you use it? Sure. If anything from a sliver of wood to plywood to aluminum to steel or a T-slot track fits snugly in a 3/4 miter slot you can use it for some application.
I just went to Rockler and looked at the miter gauge.
From their specs:
Fits both standard and T-track slots
It is designed to fit either. You can use it however you need to.
If the routed slot without a track of some sort is adequate for your application, call it good enough. I believe a nice anodized miter slot or T-track slot makes for a cleaner build, but nothing is stopping you from calling it good and using the mitered slot.
You can route both slots one for a t-track and another for a miter slot or even one for a dual track.
As far as error, just plan on doing it right. But, you are right, the width is important in an unfinished/no slot installed application.
Good luck, whatever you decide to do