Thing is, how much do you TRUST these things? If you rely on a chart or lyrics, and would be hard pressed to gig without them, do you want to trust something that might crash, battery die, or get stolen (iPads and iPhones are some of the most stolen items nowadays)?

My needed charts and lyrics sit in a ring binder in plastic protector sheets, and have survived rain and drinks, and will probably still be 'working' long after the iPad is history!

My SMF's often have the lyrics synced, so I rarely use it, but I never go to a gig without it in case the SMF don't work!

As a side note, be careful of committing important data to electronics... We will probably know more about the Egyptians and the pyramids in a couple of hundred years than we will know about LAST 50 years or so. So many of our historical and government records are being stored electronically, on data systems that get obsolete REAL quick. There's a ton of stuff on tape, a ton of stuff on those old huge 12" optical disks, and very few players left working well.

But clay tablets and papyrus lasts FOREVER!