I find this list above totally wrong:
Some of these devices can transfer Trips (many destinations routes without intermediate points you must drive one by one and you cant change when active), not Routes and are compatible with Mapsource if set to mass storage mode. For Example nuvi 34/37xx series.
Some (newer) are compatible with multi waypoints Trips sent by new Basecamp, but you cant add a Via point like in old MS Routes. For example Nuvi 2597
Some are really compatible with MS Routes, for example nuvi 1490.(active route with a unique destination with many multi waypoints)