The issue with privitizing ATC isn't so much a discussion of who can do it better gov't v. private. That alone won't necessarily result in user fees. Rather, in this case, the bigger issue is the speculation as to who would make up the private group. The consensus seems to be that it'd be a board largely made up of and controlled by the airlines, essentially turning control over to them. It is control by a group such as this that has the GA world concerned about user fees. But, in theory anyway, there are ways to avoid this and move to a private system.