I went to the local VZW store just now and tested my BIONIC with the Lapdock 100 (which is advertised for the RAZR) and the BIONIC Lapdock.
When I plugged my phone into the 100, it blanked my screen, but would not load on the lapdock. I tried numerous times, even disconnecting power and powering off the lapdock, rebooting it, etc. - nothing worked. Thinking it may be b/c of my updated Webtop from the 5.7.893, I had the sales rep try his pure stock BIONC. No dice - same story.
I then tried the BIONIC lapdock - it worked perfectly fine.
They did not have a 500 out on display for me to test.
I'm not making any conclusions, I'm just stating what my testing resulted in.