Just to add to this post to bring it up to date for anyone that come across this post this.
The major advantage of using 5DtoRGB now is that you can automatically apply the technicolor cinestyle lut, while transcoding, eliminating another step in your workflow if your shooting in cinestyle.
But I am finding an issue with files its rendering of of 422(HQ) files in that FCP7 gives a warning on import that media is not optimised for Final Cut Pro