It is great that folks like Ayoob, many gun instructors I have had including former LEOs, and that famous lawyers suggest using what the local cops use. It doesn't mean squat.
As to the question as to whether or not it could be used in court, sure, any aspect of the shooting situation can be introduced (usually) and somebody might put a spin on things that isn't great, but that goes for EVERY aspect of the shooting. Obviously, if you are going to believe that you need to carry the same ammo as the 'local' cops, then you have to carry the same gun because you will obviously need to have the same credibility with the gun as the ammo. Don't forget the holster. You need the same holster. If you have one of those nifty holsters without a retention strap, no doubt the lawyer will call it some type of speed draw holster and point to the fact that you were itching for a fight and wanted a holster where you could get your gun out quickly, without the retention strap that would slow you down.
What many of you are missing is the fact that it will boil down to whether or not you had the right to use lethal force. If you did, the ammo, gun, holster, brand name of your underwear, etc. will not be salient as to the specific shooting. As has been noted in cases in Chicago and New York, you had people producing guns for which they were not licensed, performing self defense shootings in their own homes, and not being charged for the shooting itself, but for possession of contraband. Even though they were using an item that they could not legally have in their possession, nothing about that aspect was relevant to the shooting. They were in fear for their lives and used lethal force within the bounds of the law. They were charged for the contraband, but that is a completely separate charge relative to the shooting itself and the killing of the intruders. The shooting simply alerted the cops to the fact that the individuals had contraband guns.
You know, if folks aren't going to suffer for having contraband/illegal guns they used to defend their lives in a justified shooting, do you really think whether or not a person using or not using the same ammo as the cops is going to make a hill of bean difference?
Get over the gumple (gun sheeple) garbage put out by large ego big name pseudowriter cops, lawyers with no court cases to claim to justify the points, or by gun rags. Take the time to read through some real information about shootings and shooting cases, use some basic reasoning, and make some informed decisions for yourself. Stop following the evangelic popular personalities of the gun world who seem to spout mythical realities for which they don't have justification!