I am actually of 2 minds about this.
As an owner, I think that is pretty cool and would like to see your results too.
As a buyer, I am thinking this will be another way to hide problems with a potential purchase.
Usually, if someone such as the pawn shop is selling a gun, they are not going to go thru the expense of rebluing. They, try to minimize rust and/or pitting, but it is always pretty easy to pick up on if you examine it carefully in good light.
If this stuff works as good as it claims, then it might be impossible to see just how bad a shape the gun is in. Especially if all they did was just spray on a few coats to cover the rust and fill in the pitting without sanding/steel wooling/etc all the rust and stuff away properly first.
I'm not sure I like this at all
So, it will be interesting to hear how it works for you
Doc