Don't know if possible but would love to have a Garmin pick up 2 different power meters and do some calculations with the data from those 2. Specifically I have ANT+ Hub and single crank arm meters that if I had on the same bike with a data field that read each, subtracted 3 second average from the other and divided by the hub power output then multiply by 100 would give me left / right balance percentage without having to buy another power meter to get that. Seems like it might be fairly straight forward to implement in a custom field - or even better as a software revision (since my 510 doesn't appear to be on the list of devices that will have this capability in the future)
