The American Original will be an upgrade, but not a huge one, IMO. The US model will probably be a little bit nicer in quality and playing feel than your MIMs, but it won’t be a game changer.
My own personal rule about buying new gear is that the new gear has to do something I need which my current gear doesn’t. Based on that I’d say keep the two MIMs if you enjoy them. And they can do something something that an American Original P can’t, namely be a P
and a J.
On the other hand, what the American Original P can do that your MIMs can’t is to be an American Original. If
that’s what you want or need, then go for it.