You might be right about SS. I'm not sure whether any 3C/4A types (or 2C coarse) would like it. Maybe some of them will weigh in here.
I do know that CJ has products that accomodate all curl types, despite the fact that Marsha (the owner) is a 3C/4A. Lots of fine-haired wavies swear by CJ. She has several products with protein: CJ curl fix (collagen, soy, wheat, and corn protein), CJ CQ (wheat protein), CJ Repair Me (keratin protein), and CJ strengthening conditioner (keratin).
In addition, the CJ beauticurls leave-in conditioner and the CJ CCCC lite are specifically geared to fine-haired curlies. Marsha herself uses CCCC lite only as a refresher on dry hair; it's not heavy enough to use as a curl cream for her hair type.
Finally, even the heavier rinse-out conditioners (like CJ curl rehab and CJ smoothing) don't weigh down fine hair. (They are my 2 favorite conditioners, and that's saying alot because I easily get over-conditioned).
Here's a link to the part of the CJ website that shows which products go with which hair types, in case it's helpful:
Product Selection Guide