Hi Jon...
So far, the tissue-cultured "Black Mission"-Wellspring Gdns. seems to be clean, robust, and show no signs of FMV. But, my fingers are crossed. Time will tell if the trees will stay clean. So far, so good.
I don't think virus-infected trees will survive our cold winter climates for very long. You're lucky. You live in an area that has a very long and warm growing season. The infected trees have plenty of good sunshine, over a long period of time, and possibly, are not as stressed. So, they have plenty of time to thrive, grow tall, and produce plenty of good figs.
It's the exact opposite, here on the East-Coast, especially in the colder climate, short-season areas like NYC. I personally have never seen any local, in ground trees -growing in NYC, and surrounding areas- showing any signs of FMV infections. In fact, these local trees are very robust and always have clean, healthy-looking leaves. Some have lousy figs, some have great figs, but, they are all clean. However, by mid-September/early-October the leaves do start to look ratty. Rust, yes...mildew yes... but no FMV that's visible. I don't think badly infected trees could survive, here, for very long. They will become severely stressed, and will eventually die off.
For some, FMV is no big problem. For me, it is, so I need to at least try to avoid it.
Frank