Your last link did not work for me. Do you mean "Tegra?" Here is info on that.
http://www.nvidia.com/object/tegra_mids.html

Hi Bill: Tyros2 & Tyros3 can display .txt files of lyrics and/or chords, and also have them automatically called up via REG 1-8 buttons when saved in a Reg Bank File. I recommend creating lyrics files utilzing Windows "NOTEPAD". With Tyros2 and font set at 12pt, each line char. max is 63 characters, and the page length is 18 lines, with the 19th line begining page 2, etc. Tyros3's maximum char length per line & and page length (lines per page) is slightly more.

As far as displaying leadsheets (notes/chords) you're able to display them, but only as a background image (sorry, forgot what image format), but I find it impractical on such a small lcd screen, opting to simply display lyrics and chords only (.txt) as I've got no problem playing melody notes by ear as long I've got the chord progression as a road map.

Scott[/B][/QUOTE]

The mysongbook apps supports scrolling while iRealbook doesn't. Scrolling speed is pretty easy to adjust on the fly so if the music is scrolling too slowly/quickly, you can simply tap on the speed +/- to adjust it. For performing, I find both iREalBook AND MySongBook useful if you simply require a glancing "roadmap" of the chords/lyrics of songs you're at least relatively familiar with. The big advantage of the iphone/touch size and auto scrolling is that it greatly reduces audience distraction and comments like DonM mentioned. Bill, if you already got an iPhone or iPod Touch, I recommend you purchase these apps. I found both a very economical investment. - Scott