I'm very interested in this unit. My understanding is that the unit comes with a factory installed basemap (Americas, Atlantic or Pacific) and you can add new map data with a MapSource microSD card? Does this mean while a map SD card is loaded you can't write tracklogs?
I use the Garmin Legend HCx, which is the same as the Vista except without the electronic compass and altimeter.
You can buy microSD cards from Garmin that are pre-loaded with maps, but there's an unlock process that ties it to the serial number of your GPS unit. This makes it very awkward when you decide to upgrade your GPSr. You can instead get maps either by download or on CD, and install them via USB or serial onto the storage in your GPSr (there's an unlock code, but it's not tied to your GPSr). By doing it this way you can combine data from multiple maps, which you cannot do with the pre-loaded cards.
My unit came from the US, and thus has the Americas basemap. This map shows the rest of the world as very primitive polygons. I have a 1GB microSD card in it, loaded up with more maps:
- Garmin's WorldMap, with reasonable low-detail maps of most of the rest of the world. I had to pay for this on CD.
- Maps of the Antarctic Peninsula, downloaded for free from the 'net. (legally)
- 50m topological maps for all of Australia, again downloaded for free. (again, legally)
- Detailed street maps of Singapore, including turn-by-turn routing information (again, legally free).
Each map set has a pre-defined zoom level where it kicks in. For example in Australia when I'm zoomed all the way in I'm looking at the topo maps, but when I zoom out far enough I see the WorldMap data, and further out it switches to the basemap. Overall it works well.
There's lots of other map data out there you can install, but these are the ones that have been useful to me so far. All of the above is taking up around 300 MB of the card. These units use SD not SDHC, so the largest card you can use is 2 GB. There is a software limit to the number of map segments you can load, but there are workaround such as map re-formatters.
I have my unit set to record tracklogs onto the microSD card also. The in-memory storage controls how much of the tracklog is displayed on the screen, but it saves everything into day-by-day GPX files on the card without disrupting the maps. You can copy the files to your computer by either taking the card out and using a USB/FW card reader, or simply by connecting the GPSr to the computer and putting it into Mass Storage mode.
I installed the maps on the card using the MapSource software running within Parallels Desktop on my Mac, writing the files directly to the microSD card via a USB card reader. Apparently now there's native OS X software to do the same job, but it does involve reformatting the map files for Mac use (Garmin's Mac software uses a different map format for some weird reason).
Does this mean while a map SD card is loaded you can't write tracklogs?
Probably true if you're using pre-formatted cards. With cards you've set up yourself, it's no problem.