I apologize in advance if this is already known. I haven't used routes in my Oregon 450 much so I hadn't figured this out before. I looked on some other forums and didn't see this discussed,
I'm going on a road trip in the near future. I created a route in MapSource, with several via's, and transferred that to my primary unit--a nuvi 1490T. No problems there. I'm also taking my Oregon 450 as a backup. I transferred the exact same route (actually the temp.gpx file) to my 450 and although the route appeared in the unit it could not be edited at all (the options to do so weren't present). Presumably the unit realizes that the route was created on a computer and disallows changes.
In this case I created the route to be invertible/reversible so I wanted the edit options available. Sooo... I changed the route options in MapSource so it created "direct" (point-to-point) routes, recalculated it, and transferred that. The resulting route was not only editable but the unit did recalculate it to follow the road maps in the unit.
From this I conclude that pre-calculated routes (on a computer) are used as-is in these models. Routes that only include waypoints/via's/etc can, and will be, recalculated in the unit and can be edited by the user.
Other models probably work the same way so if you experience this issue you may try my workaround.
