I have owned 5 different Mathews bows, all with Zebra strings. I never had a problem with the string stretch and twisting until 2002. The string on my legacy stretched, but not to the point that it was unworkable. The string on my LX was absolutely horrible. It stretched for 3 months. It is in my gear box now and I think it is still stretching!
Mathews owns Zebra strings, therefore, we may never see any other strings offered on their bows. My opinion is that something changed in the manufacturing process in 02-03 that was not a good.
Put on a Winners Choice string and it has not moved at all!