Those older Berninas are gems; I don't recommend getting rid of yours! I have heard that the feed dogs on the new, everything-but-the-kitchen-sink Berninas (830, I think) are too far apart to make piecing easy. My recommendation is to test drive whatever the dealer has, take notes, and then go home and think about how you want to approach quilting going forward. Ask yourself if a particular bell or whistle would be a nice-to-have or if you honestly in your heart of hearts ever see yourself using it. The worst thing in the world would be to plunk down a boatload of cash for a machine that does everything and then realize that you don't really need or want half the stuff it can do.
A newer, but still used, Bernina, like the 440 may be just the thing for you. Newer is not always better. I love my vintage 1990s Bernina.
Good luck with your decision!