As a newbie working through my pile of dirty ponies I am finding that the metal dog pet brush is great but the hair is the least damaged by using conditioner from the beginning, and the fine comb from the ends very slowly and working my way up, supporting the hair with my fingers. Letting the comb go through while the hair is dry or without supporting it seems to make it more damaged. Also tilting the comb seems to work better and keeping the damage down, and letting the hair go all the way to the back of the comb seems to increase the damage.
I have a wingless flutterpony with really superfine hair that has a curl and was a total knot. It was already badly daaaged and I had to cut quite a bit off but the remainder finally smoothed out and actually had its curl come back.
I think for the superfine hair I will try a "flea comb", the superfine comb you can get at the pet store that has superfine bristles, does anyone use those?