I record multiple stages a lot at festivals. I have three complete rigs, mics, batteries, stands, recorders. I agree with the previous replies, use 32GB SD cards and big 12V Li-Ion battery packs. Hit record and forget it. I do try to get back to each stage to check levels, check out the band, then leave again, that way I see most of the acts. Of course for bands I really like I will stay the entire concert, so the other stages are on autopilot. Make sure your record in 24 bit, and set at least 12db headroom (loud band) or more like 15db (quieter band) on the other stages, so a loud band won't clip your levels. I have TASCAM DR-680 MkII decks, which will record a maximum of 2GB to a wav file, than start a new wav file. It takes approx 1GB/24-48 2 channel, so that means each stereo 24-48 wav file is approximately 2 hours max. You could record each channel to a mono wav file, but that makes post production more work. If you get back to a stage between sets, stop and restart the recording, that way a concert won't be split over multiple wav files. If a concert is split between two wav files, you have to concatenate them in a sound editor (I use Sound Forge) and copy the concert into a new wav file. If you record in 24-96, more power to you, but copying and processing the wav files on your computer takes twice as long, archiving the files takes twice the space, and you really can't hear a difference with live recordings anyway, so I don't bother.
I usually try and record both soundboard and aud mics, when possible. Split omnis (3-4ft apart) with an XY card pair in the center is great if you have extra mics. A DR-680 will you record 6 channels, so you can record this mic setup plus the soundboard. This can sound awesome at an outdoor festival, don't recommend it for an indoor venue, as the wall/ceiling reflections will sound awful. Usually your mic setup is limited by the venue. I just got back from Delfest, you have to position your mics either side of the soundboard, so the sweet spot is out of the question, and no board patches either. However they do broadcast the main stage on FM radio, so I have a small radio with a stereo headphone jack that I record from in addition to my mics. Not quite as good as a soundboard, but close. The type/brand/model mic you have is largely irrelevant, as long it is a decent mic, but even Chinese knockoffs like Superlux can do a creditable job, especially if you just mix them with the soundboard. More important is the frequency response and pattern of the mics, hypers are a lot better when further back, and spaced omnis are great if you have them. I use Gefell M300 (cards), 3 Zigma Chi HA-FX (cards), Beydynamic MC930 (cards), Line Audio SM6i (multipattern), they all sound good.
Having said all that, when it rains, as it will at outdoor festivals, your mic stands have to properly staked to the ground (tent stakes, with a bungee cord over the tripod of your mic stand works best) and umbrellas put up over your mics. Too much work and too much to worry about for three stages, so I only tape 2 stages these days.