I haven't used many of the Brightwell products, but I hear really great things about some (especially MicroBacter7 for those keeping SPS).
With that being said, I'm not very fond of the idea of selling salt and then having to add Sodium Chloride. Sure it'll save a few bucks, but this is already a very complex hobby and IMO I'd rather pay a few extra dollars for salt that is consistant and ready to use.