According to Garmin's manuals/forums if you disable the GPS at the beginning of the run (my 610 calls it 'indoor mode') everything is saved from the footpod.
If GPS and footpod are enabled it's possible to select the speed source which is only used for instant pace, the total distance and the average pace is always saved from the GPS track, if active.
The interwebs suggest to use GPS as it's more precise on long runs, although instant pace showed by the footpod might be more smooth and consistent (unless it's used indoor on a treadmill, of course).
According to Garmin's manuals/forums if you disable the GPS at the beginning of the run (my 610 calls it 'indoor mode') everything is saved from the footpod.
If GPS and footpod are enabled it's possible to select the speed source which is only used for instant pace, the total distance and the average pace is always saved from the GPS track, if active.
The interwebs suggest to use GPS as it's more precise on long runs, although instant pace showed by the footpod might be more smooth and consistent (unless it's used indoor on a treadmill, of course).