you can use any one of those methods. The only advantage with full DB export will be that you have the option to import other users too if you later want to. And any way you need to do fromuser touser in both cases if you are importing only users.

Precautions.

1. Create the tablespaces to which those users belong.
2. Create users. (This only in case you do userlevel import, for full db import this is not required)

HTH