Twiglet, that's really interesting - I blogged recently about my eternal hair conundrum - I can never find an eco option that leaves my hair in any kind of sensible condition (it's quite long, very straight and reasonably well behaved, so if I have trouble, I don't know how someone with difficult hair copes!). I might try your solution for a while and see how I get on.
edited to add: wow, that is the first time I have ever made a link work on a forum, I think!