The poly thread cutting the cotton fabric has been dismissed many times by thread experts. This is on Superior's website: The traditions, myths, and rumors that polyester thread will tear the quilt are not true. There are many different kinds of poly to choose from.
1 Spun polyester thread
2 Multi-filament polyester thread
3 Trilobal polyester thread
4 Texturized polyester thread
5 Poly-Wrapped Poly-Core thread
Facts about poly thread: http://www.superiorthreads.com/education/will-polyester-tear-the-fabric/