A little data crunching:
PDC: average depth reported: 61'
Desktop: average depth reported: 59.3'
Xcel: (1) average function applied to all depth data: 59.344'
(2) average function omitting zero values at end: 60.475'
(3) average function omitting first value and zero values at end: 60.528'
Hi rhwestfall, I came to the same conclusion. In my opinion, there is an error in the desktop programme: In the settings menu of the DC, you can enter an "end of dive delay". After this delay on the surface, the DC will start a new dive. In the desktop programme however, this delay is taken into account when calculating avg depth. As this delay is per definition at 0m depth, you will get a shallower average from the desktop programme. The average, shown on the DC is the correct one (i.e. without the end of dive delay). Yesterday, I emailed Shearwater about this bug, and I'm waiting for their reaction... if any...
Michael