I used Duurstede for a couple months and had done a review on it:
http://www.yorkietalk.com/forums/yor...ease-help.html
But after using it for a period, I realized their coats were getting dryer, it might have been due to the winter, I don't know. But I stopped and went back to Espree products (which I never had a problem with) and that is what we use all the time now, and won't switch again.
If you are going to try it, you might want to get a few samples, not sure if the website does that or not.