Much of the break between the inner door paint, and the colorof theouter body is masked under the weatherstrip. So, do pull it all off, paint, put on new. Plus, you won't have to clean off the overspray that will get on it.
I replaced all of mine this year. Do it AFTER paint. It's very easy to put on, just get some black 3M weather strip adhesive, and use it just like Elmers glue. I would put on about 18 inches at a time, hold it for 15 or 20 seconds and then do the next 18 inches.