IMO, it's all about whether or not you're happy with the current state of your hair! The vast majority of people use sulfate shampoo and cones are get good results (or at least results they're happy with), including curlies

I went CG 3 weeks ago because I was tired of struggling with my frizzy, ill-defined curls all my life, and the logic behind the CG basics made a lot of sense to me.

I would say that I'm getting consistently better results now, although to be perfectly honest, I've completely changed both my routine AND all my products, so it's hard for me to isolate any particular change I made that really made the difference.
3a - Fine, thin, non-porous hair - boo!

Shampoo: SM shampoos

Clarifying Shampoo: KC Come Clean

Co-Wash: L'Oreal Cleansing Conditioners, As I Am Co-Wash

Hair Gel: L.A. Looks Sport, KCCC, SM Curling Souffle

DT Conditioner: SM Raw Shea Masque, SM Raw Shea conditioner + coconut oil, GVPCB

LI Conditioner: Tresemme Naturals, KCKT, VO5 shea + SM baby oil

Curl Enhancers: L.A. Looks Beachy Waves, Organix Moroccan Sea Salt Spray. AG re:coil