I think there is a major factor that might be the reason for the many broken Nanospeed 9000. It is maybe due to the fact that the stringing pattern for the NS9K series is different than the other Yonex model. If you go on their website and look at the stringing instructions, you'll see that the only high end racquet that uses a different stringing pattern is the Nanospeed 9000. An experience person may be the cause as they are used to stringing so they don't really need to check out how to string racquets. They'll use the most common way to do it. It'll somehow impress me if the person didn't do his research before to check out how to string the type of racquet.
Personally from my experience with my love for NS9000X, it is highly durable. This being said due to a few clashes I had at full swing impact and it took quote a beating before it finally gave in when I was partnering someone whom had steep and fast smashes. Overall, I would still go back to the NS9000X eventhough it gave way. I've moved down the ladder as I got a bargain for a NS8K and it just wasn't the same at all for attacking players. Don't even want to go to my back up AT800P.
