GPS V:Garmin sent me an answer!
the cartography group at Garmin answered me: "You may note, the BlueChart page mentions "limited compatibility" with the V (and other units) and this CD. "Limited Compatibility" means that the BlueChart Americas CD data will load to these units--they will draw and display the BlueChart CD detail properly. However, the "find" function will not be supported (in other words, with this CD data loaded to the V/Vista/Legend, you cannot automatically search for nearest navaids, etc. in the unit, as is possible in most BlueChart marine units). The draw will be fine, though, and most extended text screens will be available. Also, these three units do not support tide tables. Such info can be accessed on the computer. Finally, if you click on a BlueChart navaid with these units, the complete light info may not show (period, etc.) as it can on MapSource and in the true BlueChart "marine" units. The detail will draw great, though, as said."So, all in all it sounds like the GPS V might make a fine multi-use unit. If I buy one, I'll let you all know.