I think you use your tandem enough to justify buying a nice new one in your favorite color.
You will enjoy any of the options you mentioned given your requirements. While the feel maybe a little different with each bikes, you seem like some one one who will not have any problem adapting and enjoying the new ride. You just have to make sure it fit and is comfortable.
That said, replacing parts is a normal process of owning a tandem. We have 3 tandems, and very few parts on any of them are from the original bikes. Also a can of paint will go along way in widening your options. Your bike shop can suggest a paint shop if you want a more professional look.