I like Aurifil 50wt 2-ply also. It does not create much lint and is great for both piecing and quilting.
The only thread that might damage your machine (by gumming up the tension) is quilt that is made specifically for hand quilting. Hand quilting thread has a glazing on it that makes it not good for use in a machine.
Some cotton threads create a lot of lint. As long as you routinely clean lint out of the bobbin area and feed dogs, the machine is okay.
Last edited by Prism99; 02-25-2013 at 10:36 AM.