I don't know about the possible damage it might do because the Velcro hasn't been there much more than a couple of months, and I don't want to remove it just to see if there IS damage.
For years I had my radar detector attached to the windshield using the suction-cup bracket that came with it. I got tired of seeing it jiggle all the time and fall off on really hot summer days.
Velcro to the rescue. It not only doesn't jiggle, but it is covert, whereas when detectors are attached to the windshield they attract the attention of the police.
And no, I don't speed; it's just that some of Oregon's maximum speed limits are ridiculously low (65 MPH on the Interstate and 55 MPH on all other highways--even if it's a straight road across our eastern desert). My detector tells me when the buggers are out hunting.
Give Velcro a try....I doubt if it will hurt your dash.
Yodar