Played your shredderball against a MC-80 and two assault Frigates with a compliment of A-wings. Won by 30 pts. It was pretty predictable. The ISD served as a tank and absorbed the abuse till it died, which gave the VSDs a chance to command the squadrons and blow up the two Frigates.
I could see a triple VSD working well, with even more squads. My only concern would be the lack of a "tank" as it were. But I'd be willing to try it if I bad a 3rd VSD.