I started the baking soda+vinegar shampoo substitute thing a few months ago. I can't say I'm crazy about it as a full time thing, though. After three or four weeks of it my hair starts to seem pretty grungy all the time. I decided to start throwing in a shampoo at least once a month and that seems to help. Some people who do the baking soda method occasionally use Dr. Bronner's soap for periodic shampooing and I may try that. Also, if you use mousses or styling products the baking soda idea is pretty much out.
Last week I tested another Internet hair care trend going around, the "Inversion Method", which some people claim has increases hair growth as much an inch in a week. I actually measured growth of 1/3 inch, but the method calls for daily oil treatments and daily washing (for one week). Baking soda didn't do the trick at all and I used baby shampoo most of the time. You do get really, really silky hair after a week of oil treatments, though. I may continue it as a monthly thing for awhile, so I'll be curbing the baking soda thing some.