I don't have any experience with either. The airdesk looks like it's not worth the price. You could probably make the same thing yourself with a trip to the hardware store. The pro desk looks like its using components very similar to the Ram Mount, especially the tray but would at least be worth the money.
Not sure what your budget is, but have you checked with a Jotto Desk or Ram Mounts dealer (using a phone call, not a Google search)? The pricing should be pretty similar (a bit more, but far better products/support) and the products will be better engineered and worth more if you decide to sell it later.