I had a StreetPilot that I really liked, but it got so that the touchscreen would not stay calibrated. I bought a Garmin nuvi 2555LMT as replacement. Also did not know about the trade in program.
A couple of things I am not happy with you should consider. In the past I used MapSource extensively for route planning. The newer units use new software called BaseCamp. It seems BaseCamp has features to support multiple versions of their navigators, but all features are not compatible with all versions. Where this bites me is that I can plan a route with "bus" vehicle type, but when I transfer the route to my device, it does not understand what a "bus" is.
The worst part is, when I plan a route on the computer and then transfer it to the device, it gets recalculated and I often get surprised when the route ends up different from what was on computer. I have tried overcoming this by adding additional waypoints to force a specific route, but it is alot of extra work and still not foolproof.
Maybe I should have gotten the RV unit, but I use this alot in my toad as well so really did not want the bigger unit. So, seems you really need to understand how you intend to use it and make sure the software features of the unit you choose lines up with that.