I've never used their service and do not plan to in the future. GD's staff generally lacks experience IMO. If you have a premium domain you want to move, I'd suggest pursuing Moniker or Sedo agents. These two companies seem to have ties to a large list of buyers, many of whom have deep pockets.
If you are looking to purchase a domain, a buying agent can help provide more experience and anonymity. I've assisted others with buying domains in the past, most likely savings them lots of $$$$.