The SAVING and LOADING different system options is definitely the way to go, that's why it was developed.
I haven't had need to use it, but the idea is that you configure the system options the way that you want them as a system default, and then save them. You can then edit them to suit Client A and save them as Client A options. Then adapt them to suit Client B and save them as Client B options etc.
The thing to remember is that system options ONLY set a project/drawing to the chosen options at the moment you open the project/drawing. Once the project/drawing has been opened, the system options are completely irrelevant, and ONLY the Project and drawing options mean anything.
So you set the options you want and them create a project, that will have those options. Then you can load other system options and open another project. Once you return to either project they will be set up the same as the options that were in place when they were opened.