Jim, coming from Yamaha, there will be a big learning curve for you.
Having said this, the speakers are good on the PA800 and there are plenty of styles for older music.
Have you considered PSR 910? It has a similar operating system to the Tyros 3, and has onboard speakers as well. I used to play in a restaurant with the PSR900, its predecessor, with just the speakers.
My opinion is that you will be happier sticking with the operating system you already know.