I had looked at buying the pistol version and then going through the process... Deal killer was the need for another magazine type to buy to run it... plus I think the Beretta Storm even with the 16 inch barrel is lighter over all than the Scorpion...
It appears the CX4 is 5.5lbs and the Scorpion is 5lbs.
Granted, that is the pistol version vs the carbine but as an SBR I'll bet they come in the same.
The CX4 isn't an option for me because it is rifle length with pistol capabilities. The ability for the scorpion to get nice and compact for CQB work was the deal winner for me.