You need some kind of anti-corrosion agent in the mix. I don't know if the "water wetter" has it or not. I think you'd be better off with a 50/50 coolant mix. With a basically stock system, if you need "water wetter" or "Purple Ice" or whatever, somehthng else is wrong.
"G.M.", not to be argumentative, but I would think that anything that "coats the inside of the water jacket" would insulate it and retard heat transfer, not enhance it. I have not used anything but an antifreeze/water mixture in vehicles with cooling systems in good shape and have never had a problem. Sure, I've dumped in a can or two into a beater that sprung a leak driving some place, but I always ended up fixing the problem and going back to a straight mixture.