I have both at the present time,though the 970 is up for sale for $900 mint. I decided,initially, to upgrade to get CDG playability,touch screen,and better speakers. I got that and more. It is taking me a while to get used to the new OS,but, with the same basic, familiar operation of the PSR.
The specs show many other additions,like more memory,styles,voices,and chord memory etc. The most striking difference,for me,is the detailed,more live sound in general. I am very happy I made the switch.
_________________________
pa4X 76 ,SX900, Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact