I always advocate getting the watch fixed locally whenever possible, for the following reasons
1. The factory movements frequently, if not always arrives dirty and poorly lubricated. Exchanging one watch for another does not resolve this issue. The replacement may or may not be running well.
2. Transit shipping itself poses a risk, both in terms of custom detention, loss or possible jolting or rough handling of the watches. Screws, rotors and even springs can become dislodged in the process. The dealer will claim he sent a perfectly working watch, but you may receive junk. Such mysteries are often solved when one realizes how packages are handled during the shipping process. I have seen cockroach carcasses get treated better.
3. The dealer does not really resolve the issue of the watch, but rather, replaces it with another one, which may have a different issue. That is watch repair for you in China. The cost of replacement is far lower than the cost of proper repair/service.
4. Getting the watch serviced properly is an upgrade, in terms of movement cleanliness, lubrication, and time regulation. It will ensure that your watch keeps good time, has a healthy power reserve and is reliable (as reliable as the movement design will allow), and helps you ensure that you will enjoy your watch for a longer period. Of course, if you are buying a watch just to try it on for fun, then forgo the service. But if you really like the watch and want to enjoy it properly, then get the movement, the heart of the watch, in a healthy and pristine condition.