Scraping that much and you left it on....braver than I. I wanted one when a friend got his, but after see someone lift the rear wheel off the ground (on a different bike no wheel dock) I decided I dont want to take the extra chance, especially since my better half is usually with me.
I have already sheared off a Kury flip blade over a curb turning into a driveway. I can imagine what the wheeldock will do.
The only time I bottomed mine was pulling out of a gas station where there was a deep dip between the lot and the road I was pulling on to. It was not an issue with the wheeldock because I believe I would have bottomed out the frame had the wheeldock not been on.