MatthewG, I just got the topo software for my Magellan Meridian Gold yesterday. I am very UN-impressed with it. The topo contour lines only show every 100 feet of elevation change.[:@] So, if you are hunting in a relatively flat featureless area, it will be worthless.
The topo software does, however, show the majority of the old logging roads, 2 tracks, and streams/creeks. The topo software is the same as the street/destination software, with the addition of the topo lines. If I were to do it over again, I would probably still buy the topo software, due to the fact that it has all the same features as streets/destinations, with the added detail of small roads.
With that being said, I may change my mind on the detail of the topo features once I plug it into the GPS and use it, but on the computer, its a definite bummer.

Will it float? Sure will, but I dont know for how long. Hopefully I never have to find that out.