Do "Chinese Ironwood" cutting boards dull knives quickly?
Based on its density when compared to other hardwoods, I would say it would (see here). Also, having used one (I had a nice circular board, when I lived in China actually) and I noticed it as well. Just like you say, in order to keep a good edge on my knives I was sharpening more often than I was accustomed to with my endgrain cutting board (made myself out of maple and walnut) as well as my bamboo one.