When I replaced the engine in my car, I also put on FlexFax, even though 2 months prior I had djust repalced my fan clutch. I've had no problems with the FlexFan, plus it's much lighter over all (which translates to less drag on the engine, but nothing noticeable I'm sure).
Since I clean my car regularly, I'm usually checkign things while I clean, and cleaning the fan blades is one of the areas I clean. And why not? It's easy access and they are aluminum, so they look better when clean
Anyways, since most of the time the engine is running is when the hood is down, I'd rather have the flex. Should either of the two break, the Flex will likely do less damage. And even if the hood is open and you're over the car...one note was that the FlexFan lopped of an arm, another was that the clutch went through the hood or radiator. I don't think our mushy bodies would hold up much better than a radiator or fiberglass hood!
So that making the "possible dangers" a moot point, I think the FlexFan wins the actual performance benefit category.
Two things on the side:
One, now that I have my video production system in just about full gear, I'd be more than happy to make a small clip of the flexfan in operation.
Two: I have a relatively new clutch fan if anyone needs one!
My FlexFan