I've recently switched to " 1 second recording" and find that a 7 hour ride uses aprox 644kb of space, so there is plenty of room for a good few rides, but I like to keep on top of things and delete histories and locations quite often, nothing worse than a ride being ruined by running out of space. On my old 305 if I recall, I could only ride for about 2 1/2 to 3 1/2 hours before I ran out of space with just that one ride.
As for locations, I like to keep things tidy and hate having to search through lots of locations, most of which can be miles away, I create files for different areas I ride in with "Mapsource", then I delete the "Location" folder in the 800 and then load the required file. Ie this weekend I'm riding an Audax at Hebden Bridge, so my "local area" location file is deleted, and my Hebden Bridge location file, with only about 20 locations, which I will pass through, is loaded into the 800 once again with Mapsource. Usually as well, I name my home location with "0" so that it is always the first in the list and easy to find whilst riding and also locations I pass through, I prefix them in numerical order so then I do not have to remember place names. But what I cannot understand is, locations seem to be in order of the nearest and not in numerical and alaphabetical order, but why is my home location "0" always at the top of the list, regardless of how far away I am from it and other locations being nearer to me? even "1" or "2" or "3" do not come in order after "0"?