I did try using mesh discs a while back thinking they might be the way to go, they are ok for some aplications but ultimately went back to regular sanding discs.
The major problem is that you need to fit a protective sacrificial pad between sanding disc and sanding pad or you will quickly wear out the velcro.
The protective pad made the whole thing a bit soft for me. They also tend to wrinkle up quite easily and tear.
You can buy from the Sandpaperman if you want to use them.