really, you can use any thread you like to use!
if you really look around you will find that (most) long-arm quilters use polyester thread. it is what works best in our high-speed machines and has the best color selection. holds up to anything. i have become very attached to my silk threads for any and all hand stitching. i use silk for hand piecing, for applique and yes for my bindings. I seldom use cotton thread. it breaks way too easily and as far as i'm concerned one of my biggest wastes of $$. often i use up what ever threads are (left-overs) for hand sewing, that little bit left on a spool or on a bobbin. i only worry about fiber content if i am having a problem with the thread...then i look to see what it is...usually cotton; kick myself for buying it again and swear i'm going to pay better attention next time.

I have heard the myth about polyester threads too... I have no problem at all using the ones made today :D:D:D