Very much so, although I don't recommend it unless you do know what you're doing... Personally, as I don't do multiplayer, I've simply used ETO as a source of bits and pieces, and discarded the rest. At the moment, the 'issue' scenery has become too heavy for me to run it properly, so there, for example, I've used some of the elements to build my own. And so on... But as I said, if you're not sure of what you're doing, be prepared to spend a long time figuring out why it doesn't work! And fixing CFS3 at a distance is no easy task.