I've been no poo for over 2 years now. However, I use the baking soda wash/ACV rinse method. I would love to go water only but I have long, straight, somewhat thin hair and the greasiness is unmanageable. Here are my thoughts and I welcome any/all feedback:
The soda/ACV method does actually remove the "excess" sebum from the hair but does not strip the hair. I can tell very clearly that my hair is coated with its own natural oils and is not dry at all. I brush with a natural boar brush about twice a day but this does absolutely nothing to remove or move oil - I can brush and brush and the hair near my scalp is just as slick and oily. This after 2 years of no hair product or shampoo.
When I first transitioned, it didn't take me 4, or 6 or 8 weeks to adjust - I'd say it took a solid 6 months, seriously. This is partially due to my learning curve about how much baking soda, how often to wash, etc.
Prior to no poo, I could not grow my hair longer than my shoulders - it would be like straw. Now its soft, shiny and I've got it way down my back. My hair looks and feels healthy - NOT dry and I use baking soda in water with ACV rinse between 1 and 3 times per week.
Bottom line - water only I don't think works for every hair type, definitely not me but I'd LOVE to be more natural and have more no poo benefits so if anyone has any techniques or advise for me - I've love to hear it.