My basic set up is like yours, Scott. I have a couple of genre setups, plus approx 200+ songs ready to go at the push of a button for the usual dinner/dance situations. (I also do this with the PSR740...but it requires multiple discs.)
While most of my bookings are as a single, I also have two girl singers I work with in duos and have created individual set ups for each of us. This just assures the key sigs, tempos and styles suit each individual performer.
And for the 1-hour Senior Shows at assisted living and nursing homes, I have yet another setup with a much more limited repertoire, allowing me to access what I need almost instantly without having to punch up a bunch of pages. Should I need something I don't have on the Senior Disc, I just load my Singles Disc and usually am up and running inside of 30 secs including a little banter with the audience.
Pre-programming and saving all the registrations is a lot of work with unending tweaking, but once it is done, it sure makes it easier to concentrate on programming to each individual audience.
Seldom do I need more than 5-10 seconds from one song to the next. The great thing about the PSR2K it is adaptable to several preferences of performers. But, like you, I can't imaging Uncle Dave doing all this on the fly.
Eddie