It all may depend on your hair properties. My fine/low porosity hair really likes cleansing with soap bars (alkaline.) I used to do an ACV rinse, but stopped because I figured that the products I used had the right pH for hair (wrong with these products.)
Years ago, there was a product (Dr. Bronner's Shakakai Rinse that had a really low pH (I forget be it was like 2 or 3.) While my hair didn't care for it, those with coarse (I forget if it was porous also) hair loved it.
The other thing to remember is that the cuticle on your hair isn't like Venetian blinds. It doesn't open and close quite that easily. I think you need to take the "science" into account, but you also need to be realistic about what really happens.
3a (Corkicelli), highlighted, fine, low porosity
modified CG, since April '07
CG since 3/11/08
HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me