Since the advent of the Yamaha PSR-S-950, the lyrics can be linked directly to registrations, thereby displaying them on the screen the instant the song is selected. This is a great feature for OMB entertainers and really helps eliminate dead time between songs. However, you must have pretty good vision to see those tiny words on the screen, which is something most of us do not have. Therefore, I'll stick with the 9-inch netbook PC display, which I use a white background and bold black letters.
All the best,
Gary
Let me throw my 2 cents into this. I recently converted from a smaller model iPad for lead sheets to the Pro12 tablet. JerryGr sold me on what a cool device the Pro12 tablet is with his post here TonyMads got interested in it too. I worked with Tony to get him up to speed on its use helped him configure his PA900 to talk to the tablet.
With that said to date I've got just over 100 of the most popular tunes I play at senior venues talking to my Pa4x choose anyone of those 100 from Songbook on the Korg and the lead sheet will immediately be displayed. At the moment for a gig I'm playing tomorrow I created a 52 custom list in Songbook, when I choose that Songbook entry the lead sheet is immediately pulled up on the tablet, it will work in reverse too i.e. if I pull a lead sheet on the tablet the corresponding style and instruments will immediately be set on the PA4x. I've also set both the tablet and Pa4x to pull up a midi file and the lead sheet that matches.
The search function on the tablet is instantaneous as well, so even if I get a request for a tune I don't have in Songbook I can at least immediately get to the lead sheet.