Basically it allows you to hook up more non-strapable amps (or strapped pairs for that matter) to a single sub. It adds some flexibility as well but generally people using quads are tryying to get more amps hooked up.
If it is just for a daily driver and you don't plan on competing, the I would recommend the dual VC option just to make wiring the sub(s) a little bit easier.
nah, but when you're talking about multiple amps for a single sub, that's getting into the "pretty ****ing serious" power level...//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif