All, thanks for all of your great comments! For now, it looks like my chainsaw count will stay the same, and that's a good thing!
When I was talking to the owner over the phone about the tree, he stated that he was interested in referrals from some good tree removal and service companies. He had spoken with a few and they all felt that the tree had to come down (it had lost a limb that was almost 4' in diameter); but most of these companies specialized in removals. So, I referred a really good service company to him and let him know that if anybody could save the tree, Cormac could.
Two afternoons ago I stopped by to look at the tree, and it was everything that I was told, and more. The canopy had to have been at least 150' wide, if not more; it literally spanned the entire width of his lot and on one side extended quite a ways into his neighbors back yard.
In studying the branch that came down, I noticed what appeared to be some rot in the heart wood, although the leaves and the rest of the tree looked healthy. I also felt that the tree could be saved (as did Cormac), and recommended to the owner that they try to save it yet keep a close eye on the overall health as time went on.
Thus, I do not anticipate any mongo logs in my near future (and that's good - I hate to see something like this come down).
Anyway, y'all asked for pix, and here are a couple for you. They are pretty self explanatory. The owner is pictured next to the tree, standing on a burl that's near the bottom of the tree. In one photo you can see the broken limb.
If it does eventually have to come down, I hope that the rot that I observed does not extend into the main trunk. Que sera, sera.
Impressive, to say the least!