30SC in a carbine is an interesting idea, but to what end? You can shoot the +P 9mm of your liking and I doubt you'll get similar performance from 30SC. Does 10% extra rounds in a mag really matter if you have 17 or 30 round magazines? Unless 30SC costs less, which I doubt it ever will - it is fine, interesting, but - in a carbine I don't see it doing anything unless there is some magical ballistic phenomanon I'm unaware of. In a small/medium sized handgun I think it is a particularly good idea, we'll see if it catches on.