I may be wrong but if I remember right @KiwiMoose doesn't use C-Betaine because it is an irritant. If you are making shampoo just for yourself, and are not allergic to it, it would make formulating much easier. It is a gentle surfactant, and not "more chemical" than SLSa or Amphosol. (I'm not quite sure what "chemical" means anyway....)
I like formulating my own things too, but for formulating a good shampoo it is quite essential to have some accurate pH testing device, which I don't at the moment. So I don't try to do it from scratch because in terms of pH it is very difficult if not impossible to calculate where you end up, without actually testing it.
FWIW, as mentioned in another thread, I recently got a commercial syndet shampoo bar and quite like it. It has plenty of lather. They don't use SLS (nor coco betaine as far as I can tell), so it is certainly possible.
LOL I have been following that thread and OMG 26.00 I find a little crazy. But having said that I will never say never cause then I might have to eat my words.