Thanks for the reply. It's never an easy job with trees like that; you just give your assesment & recommendation and let them come to a decision.
I had a big (34") mulberry like that a few weeks ago, and the HO did not want to live with ANY risk. I told her she would have to start with removing all of her trees. Ultimately, the decay at the base of the mulberry proved too scary for her (I recommended reduction pruning and monitoring), and she wants it removed. Haven't heard back, I guess my quote was too high LOL.
-Tom