Any thoughts about whether it's worth taking a risk on a GTX470 with the black screen problems still unresolved? Occasional 3D crashes don't bother me, but I must have 100% stability for normal desktop work.
I'd lean yes. This appears to be a driver issue and it's also pretty rare.
If you need near perfect reliability and stability because of your work, you're going to have to make some compromises on the gaming side. Any new card or chip is going to have some issues, and overclocking is going to put additional strain on the processor, memory, motherboard and video card.
Maybe you should think about a motherboard with integrated graphics that you can use as a backup for desktop work in case your gaming video card has problems?