Here's a link to why you shouldn't use it
http://www.thequiltshow.com/os/blog.php/blog_id/3800
"Can I quilt with serger thread? Bob Purcell says yes, but why would you?
Most serger thread on the market is the cheapest type of spun polyester thread. When used on a serger, multiple strands of this thread are over locked, resulting in a strong and secure stitch. However, if used as a single thread for quilting, it is weak and fluffy. It doesn't make sense to put two dollars worth of thread onto a $300 quilt. Inexpensive serger thread has a loose twist, is not very smooth, has lots of lint, and is not intended for single-strand use.
This great tip was found in the School of Threadology Manual. The book and accompanying DVD lay to rest many of the myths we have heard for years, as well as a great 'hands-on' tips to make your sewing smooth sailing. For more great thread tips check out the complete set available through Superior Threads."