Yes, claybar is WAY more proven. Vinegar is used to take out calcium and other minerals in the paint. I lightly rub it on and then right back off. I know it's acidic. That's why you don't do it every time you wax, more like every year or so. I used it on my car and I'll try to show some pics...(can't right now because they are at home.)
This is another case of using a product when it's not necessary. Vinegar is one of those "last resort" types of products. Clay bar followed by a paint cleaner/cleanser will give you the same end results - clean paint. Once the paint is clay barred, cleaned, polished and sealed you should never have to use vinegar, let alone once a year. 