I have a 5DII and wanted to confirm that the 600EX-RT will work with it to deliver HSS.
Here
is a link to my blog post describing how I tested and with examples showing the results.
Good news is that it works, both in ETTL and Manual modes. Ratios also work and in Av mode on the camera FEC and EC work together as one expects to control ambient and speedlite exposures.

