Doc,
The two new Yamaha YPG525 and YPG625 both feature a full keyboard style play mode which allows you to play anywhere on the keyboard and the style will follow your playing. Plus, they both feature registration memory which would allow you to save your styles and sounds to play songs you put in memory. Because these two new models feature a usb device port, you can save hundreds of registrations and load them as needed. And both are lightweight and feature 88 keys. I'm recommended either of these because there would be very little to have to relearn. Price range on these two models are from $650 to $750. The 525 has keys like your DGX505 and the 625 has hammer weighted action, more like a piano would feel.
George Kaye
Kaye's Music Scene
Reseda, California www.kayesmusicscene.com
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George Kaye
Kaye's Music Scene (Closed after 51 years)
West Hills, California
(Retired 2021)