I had kerastraight in may 2011 and can not speak highly enough! It didn't take my curl away, but de frizzed when air dryer and was just amazing when rough dryer it fell to a slight wave with silky straight ends, and to blow dry straight was cut from 45-1 hour down to 15mins!
It has only over the past 2months completely washed out but even now I can still feel the benefit when blow drying.
I would recommend it on white curly hair anyway as I love it, saving up for my next treatment!