I just bought my third pair of these.  I wore the first two every day for several years until they started fraying at the bottom.  The new pair is just like the previous ones except the fabric feels softer, similar to a microfabric.

The expandable waistline doesn't work as well as I would like it too.  It is controlled by elastic so expanding more than about 1/2 inch would put a lot of pressure on my abdomen.  But as long as I don't gain weight the pants work fine as is.