Master/hard reset will do only three thing what you can see.
The first. It deletes all waypoints and tracks that you can see in device in current.gpx. So if you are interesting for reservation of waypoints you must make copy for restoring!
The second. It restores all settings to default. You must make you favourite preference settings again!
The third! It erases all last results for searching in Goto and predicative promptings for its.

And forth for desert! After Master/hard reset all Garmin device merely work better then before it. Trust to my experience!