I don’t understand the "rod embedded with grit" argument.
If it is grit that is left over from the firing of a cartridge, then the firing of that cartridge and another cartridge and another cartridge, etc. will cause more damage to the bore than me running a "grit embedded" aluminum, plastic or carbon cleaning rod a couple/three dozen times down it.
If it is grit (dirt, sand, dust, etc.) that has found its way into the bore at the range, then once it becomes imbedded in the cleaning patch, swab or brush and I continue to push that patch, swab or brush through the bore of my firearm, the same "embedded with grit" argument holds.
I don't know anyone who throws away their bore brush after just one use and the brush is in contact with the bore for the entire duration of the cleaning stroke so are we damaging the bore by using an old "embedded with grit" brush?
I doubt any of us are damaging the bore of our firearms or even the crown (to the point where accuracy falls off of the table) by using stainless, aluminum, plastic or carbon cleaning rods.
Use what you're comfortable with and can afford to use.
All the best,
Steve