I guess at some point you have to trust your gear OR run two completely separate rigs if the recording is that important.
I find myself often doing this. For most of the last decade as I've taped, I've run two recorders. First with mini-disk due to the media swap, then with DATs since they always proved to be finicky and unreliable to me, then with the Nomad JB3 since hard-disk recording was so new to me in 2002. I've just continued since then.
Now I'm either doing an easy two channel rig, or more than likely for the "bigger" shows I run two sets of mics, two preamps, and two recorders (one being the 680). So I end up with the two sets of mics+preamps going into the 8ch 680, and then run a separate Sony D50 out of the aux 1/8" out from my littlebox. That ends up being a fully independent rig at that point, with 2ch of mics, preamp, and recorder separate from the other set of mics>preamp>680. I keep toying with the idea of getting an M10 so I don't have to take along the larger D50, but I have a hard time skipping the 2nd recorder precisely because adding that small recorder into the mix gives me a complete backup system.
Probably makes me a paranoid freak, esp since there are other tapers at almost all shows I record, but I can't help it.