I'd see what we but any bike etc would offer, might be more than the dealer.
Selling privately should get you more than the dealer offers, but then you have to hope you meet sensible, level headed, considerate people wanting to buy it, and not just tyre kicking time wasters who agree a price and then try to negotiate you down when they come to pay.
When I swap bikes I tend to go with the dealer option as it's a lot less hassle, and the profit they make is keeping them open for when I want to get the new bike serviced etc, YMMV.