We had the same problem. I would just get the line cleaned every year.

I don't believe many residential homes have a 6" sewer line. Even if they do install a 6" access - the roots will still grow back after a year or so.

Cleaning the line if done properly will not make the problem worse. Roots get into the lines from cracks in the pipe, cleaning will not make the roots more aggressive or damage anything. I have to have my sewer lines cleaned out on occasion, but I do an annual application of RootX which will burn the roots to stop them from wanting to come into the line in the first place. I would be leery of a company that sends a camera down the line right off the bat, that's usually a expensive thing to have done to diagnose problems, sounds to me like they were fishing for expensive jobs.