So, the guy came, and he was friendly, knowledgeable and thorough. He spent over two hours looking and explaining. Long story short, the pipe is fucked. There are no tree roots, but there are major deposits and lots of rust. It's likely that the pipe is paper thin along its bottom. There's standing water in some places (though not very deep), and when he pulled out the camera, there was dirt (like dirt from the ground) on it.
Digging is not a very good option, as there is a large (and I mean LARGE) tree at the curb line, right above the pipe. Either the tree would have to go or they would have to open the street, which runs into over $10K just for the permits and insurance and paying two cops $65/hr to direct traffic (we see maybe ten cars a day on my street),
The other option is to hydro-blast the crud out - they can vary the pressure from 10Kpsi to 50Kpsi which will leave the pipe clean and even more fragile. Then they would reline it with this stuff: http://www.brokensewerpipedenver.com/perma-products-systems/perma-lateral-air-inversion-lining-sytstem / which leaves about a 3/16" very smooth plastic wall inside the pipe. This involves jackhammering in two places in my basement - one to bypass the whole-house trap wich is no longer required by code, and the other to gain access to the pipe just past the main stack. There is no digging required outside.
All this comes with a lifetime warranty, transferrable once, and a price tag of $7700. It takes a full day (he says there are three trucks and six people here all day), and then its done.
Good idea? Bad idea? Run like hell?