When they were new did you re-tension them? The tension needed is much higher than a steel spoke because they are thicker and of a different material. I'm over a year on them, and everything is just as good as day one.
I retensioned, and retensioned EVERY time i broke one which became basically once a ride, just too much of pain in the butt for me to deal with. I'm not a heavy guy (170) so i don't know what the deal was, maybe the way i ride or what i ride but I'm personally alot happier now on my DT Swiss wheelset. And I'm not hacking on I9, their customer service was awesome, but i'd hate to do a road trip to say Nelson and have to buy new wheels because no one has spokes for them or a Park tensioner.