I've got the 9mm. I bought it when I was planning to buy an M9, then I decided I really wanted a 96G, but I already had the 9mm CX4 so I ended up getting the M9 anyways.
I think the .45 caliber CX4 is a great idea, but a poor execution. I just can't see owning a pistol caliber carbine with a single stack magazine.
The .40 vs the 9x19 is really a toss up in my opinion. I prefer the 9x19 simply because of slightly cheaper ammo and an edge in capacity. The availability of the new "sand resistant" 92F magazines is a bonus as well, in my opinion.
Overall I've been very happy with my 9mm Storm carbine and don't hesitate recommending it. The Winchester 127gr +P+ Ranger T loads really scream out of the carbine length barrel. Me and a buddy were taking turns plinking at a stump at ~120 yards with that load and we were both impressed with the accuracy of it.
For your purposes I think it'll be great.