I just went out and did some testing on the MobileMapper 6 and ArcPad 8. It went wonderfully. I created a geodatabase, checked out files, collected and processed GPS data, then checked the data back into the original Geodatabase. A classic ArcPad project. It went off without a hitch, and with post processing it should be submeter data.

I recently had a customer report some issues with the post processing and ArcPad 8. MobileMapping Office didn't understand the coordinate system and the data would disappear after processing. Poof gone. The files automatically back up, so there is an undo, but all the data disappeared from map view.

Turns out the PRJ file had been changed. Although he had set the database up with Michigan State Plane in Intl Feet, the PRJ file indicated Meters. This must have sent MobileMapping for a loop. We have no idea how the PRJ file was changed...A new geodatabase was constructed and everything was fixed.