Mag Chloride. The stuff makes a giant mess. The article I linked says it is less corrosive to steel, but then later down says it is corrosive to aluminum and steel. Still, you rarely see vehicles rusted through around here. That might have more to do with the dry climate than the road salt, but I don't know.
BTW, for what it is worth, when I bought my VX the ABS light wasn't on, but it turned on while I was driving it off the lot. If I had known then what I now know, I would have turned it right around and gotten $3k dropped off the price. Still, for what it is worth, mine has been 'broken' ever since, and I haven't really missed it all that much.
An ABS light impacts the price, in my humble opinion, but does not impact the overall quality of the VX. Having the brake light on is a bit more troubling. It COULD just be a problem with the handbrake, but it could also mean that half the brake system is dead. From experience, I can tell you that you don't want to drive around with half your brakes.