Hi John,
I am surprised you've opted for Yamaha as being the first choice as I think the operating system is very antiquated and could do with a huge update. For a start, you cannot play any of the Technics on it without a conversion, whereas from the demonstration I had at Pakefield last year, the Korg can play them. Then there is all the button pushing to get to songs, styles, registrations etc., which is VERY time consuming. Having said that, I have the Tyros 4 which has a really good sound system and I get a great deal of pleasure from playing it, particularly as I now have many converted Technics styles that I can use - a real bonus believe me.
I recently had the opportunity to play an Orla keyboard and I would say for beginners (particularly seniors) it would fit the bill nicely as what you see is what you get.
e.g. all the buttons are clearly shown on board and by 1-3 button pushes it will bring up your choice(s) which can then be saved instantly. Also for the organ enthusiasts there are quite a few organ voices on it and in fact, my friend calls hers "My mini portable organ".
Just my opinion of course.
Audrey