The good thing about the resin version would be the better chance of getting sharp details. Now Im not saying that the all metal ones wont, its just that it would be much easier to cast them in resin. Like on the two pointed details on the back portion of the pistol. I can say that the resin will get those just as sharp and pointy then I would imagine with the aluminum version.
But I dont know yet, but thats just my take on it. An all metal version would be cool, and I wouldnt worry about the barrel snapping off.