Robert,Very good question that I’m sure will prompt a few opinions. I like using the out of box security groups as they provide a good base for incorporating changes to permissions. If you aren’t very familiar with Project Server security you might want to copy/create your own so that you can validate what you are changing. It would be a bit of work (and a bit of risk to make sure you duplicate them correctly), but using out of box security groups/categories won’t cause any issues with future releases. Hope that helps.