When there are two power sources (trainer and powermeter), the "power" field of the .fit file always contains the power source that was used to make your avatar move in game. The other power source is saved in a custom data field.

I would like an option to always save the preferred power source in the "power" field of the .fit file, even when the game effectively uses the power from the trainer to make the avatar move. In this case the power from the "non-preferred" source would be saved to a custom field.

The problem with the way the .fit file is currently generated, is that when you've entered a race that enforces power from the trainer, all the platforms the .fit file is uploaded to will use power from the trainer for their analytics. Even with a perfectly accurate trainer, it will skew your metrics by 2-4% due to drive-train losses. I don't mind that TPV uses power from the trainer to make my avatar move, but I want my 3rd party tools (Xert, TP, Strava...) to always use the power from my powermeter.