I use an iPad with BIAB-generated lead sheets as well as scanned-in Realbooks on my iPad, using 'unrealBook'.

I usually play (guitar) with a clarinettist and a keyboard-player, but I've prepared MP3s for the majority of our BIAB repertoire with the melody suppressed, and a default of four choruses (head, clarinet solo, guitar solo, head).

This came in handy when our keyboardist (who supplies bass and drums as well as piano) fell ill and had to go home just after setting up for a gig. I was able to connect my iPad to an amp and run the tracks directly from the iPad with the lead sheet on the screen. unrealBook allows you to link any given chart to an MP3 file copied to the iPad using iTunes in the normal way.

There's no reason why you shouldn't use BIAB live from a laptop - we've done gigs that way too - but although this gives more flexibility than the pre-recorded MP3s it also gives more scope for error - e.g. forgetting to switch off the melody track, or using a file which has been tweaked for practice purposes and inadvertently saved at the end of a session.

My iPad will run for 10 hours on a charge, but if you want to connect one to a charger remember that you might have an earth loop causing hum (as you would with a laptop). Best to try it out on the equipment you're going to be using BEFORE you get to the gig!, and consider getting an isolating transformer (for the mains supply or for the line-out signal).

Hope this helps.

Michael