As I'm icing my left foot after the race to relieve the swelling under the ankle I'm browsing the web to see if something new showed up about RS800cx and see what I found on Polar site.
From the pictures in this support article Polar released over the weekend it is apparent that the RS800cx will support 3 sets of shoes each with different calibration factor for each and 3 sets of bike/wheel configurations. From the picture it looks like you will be able to indicate whether the G3 sensor is used for the exercise (but that does not seem to be shoes specific). I'm not completely sure what is the GPS Distance parameter used for, but I guess the user guide will answer it. And as for the RS800 you can pick speed units you want to see on your screen, auto lap distance and lock zone settings. For the bike side of the picture it does not look like the power sensor will work with this watch. Oh well we kind of knew that from previous info, but I was hoping this would change. Interesting is the remark about calibration that is done in meters only - indicating that even in countries using imperial units the track is 400m.