I have, and use, Voltwatch on every one of my planes. It is relatively cheap insurance. I check the voltwatch before AND after each flight to make sure that the batteries are in good condition.... before I fly to make sure they are ready to go (especially on the first flight) and after each flight to make sure that they are adequately charged for the next flight. If not.. on the charger they go.
I also have a dual battery - dual switch setup on my 'expensive' planes. Two batteries, each in a separate RX channel, and each with it's own switch. I also use 1200 mah NiMH 6 volt packs. (Spektrum DX7 system.. great system!!) I won't say that I have eliminated problems, but I sure have removed some of the potential for problems. And, I don't take chances when the charge is 'borderline'. It's just not worth it. I also have an ESV, by the way, just to make sure things are ok, and use it... not just depend on the Voltwatch.
BTW, I'm happy to read that you found your plane. I've not lost one that way.. yet.. but we do have a rather large flying field, so that does not happen all that often. Nope. When ours fail, they go crashing right in front of us.. well, almost.. [&o]
CGr.