They are nice units but not the Garmin breakers they were meant to be. This was not a 12 channel parallel unit and clearly came in at the bottom of any comparison. Magellan then released a 12 channel version with similar features call the blazer 12. Please see my article on Blazer 12 vs. the G-12 for a table comparing these units. The major differences in these units is the addition of a case for the 320 and it comes pre-loaded with a navaid database.
More details are available at the Magellan web site .
I have updated the table below to match the Magellan release 3.12 and to add the new Garmin etrex product. Y means feature is present, N means not present. A model number means feature begins with the model and is not present on family members below this unit. There are features of Magellan Tracker family products and other Garmin products that are not addressed in this table. It is a specially packaged 315 so the table applies to it as well.