Thats the $1300 dollar question! That "protection" value is directly related to the "fail rate percentage". Aside from charging issues... how much failure are we gonna get? If you bring a laptop to hard wire in case of bad wifi that has to cut your percentage seriously really low... right?
That's definitely safe to say. There's the danger of dropping the iPad, so a good case like the Griffin military rubberized case is a good investment. That one has saved my iPad several times. But I have yet to see one actually die from failure. And yes, I always have my Macbook close by.
There's a couple of drawbacks with the tablet idea to deal with... You need to turn off the auto lock, or the screen time-out feature on the tablet. If you don't, and with iPads, anyway, if it auto-locks, you'll have to reconnect to the mixer after it wakes up. So that makes another dilemma. Battery life with the screen being constantly on. dimming it down will help, but it's pushing things to get 4-5 hours from a constantly-on screen. On breaks, you can manually put the iPad (okay. whatever you are using, iPad herby means whatever tablet is in play here). For sound guys, you need to establish a "docking location" with a charger in the audience area somewhere that you can default to if the battery runs low. For musicians running your own mix, once your mix is set, you can put the iPad/iPhone to sleep and save battery life.
Also, I've found that if you run the iPad on the 5gHz band of your router, you usually have less devices trying to ping it, although that's less and less true as time goes by. There's tricks to try (no SSID, using Mac address filters, etc) to keep devices off the network. Let me see if I get this right, and any IT guys, please chime in here, but when a device sees your network, it actually connects, but it can't log in. So it can get bogged down and slow down your connection (that's when you move a fader on the iPad and 4-6 seconds later, something actually happens on the mixer). When I started running into this a few years ago, I discovered that my connection ills subsided when I moved to the 5Ghz band (even though the range is decreased, I haven't had range issues, even in big coliseums and arenas).
Hopefully, most of us playing clubs and small events won't run into issues of this magnitude, but a little planning ahead still makes wifi/iPad life a little easier.