Look how far we have come with Yamaha keyboards. A fellow back in our earlier days played the PSR 6000. Then another fellow came later with his PSR 8000 which was a monstrous beast to say the least but it gave great sounds for dancing. Then there was the PSR 9000. Not much difference. My first keyboard was the PSR 1100. For me it was fabulous and I really enjoyed it. When I heard the PSR S900 I had no choice, it was my keyboard of choice. I wish I still had it. I sold it to a needy person and bought my Tyros 4. Have never regretted that and it will be with me for ever. Next in line was the Genos which lasted just a few weeks before going back. Then the SX900 which followed the Genos after 3 months. Now I have my Tyros 4, a PSR S970 and the SX700. I use the PSR 970 for playing out and the SX700 just for information when discussing with others.
This is a list of the keyboards I have heard in that order. Be prepared for "Look how good I am at playing piano" from some of the demonstrators.
You don't have to listen to the whole video, just some parts in the middle of each. The demonstrators seem to like blasting you with heavy rock, twanging guitars and bashing drums with them trying to show off their piano skills.

Do a right-click to open each of these up in a New Tab.
Yamaha PSR 6000
https://youtu.be/AvL1aUfHGiw
Yamaha PSR 8000
https://youtu.be/oB4Jo-W_M9Q
Yamaha PSR 9000
https://youtu.be/EXdybFfKBUM
Yamaha PSR 3000
https://youtu.be/JUJBDjZ2wL4
Yamaha PSR 1100
https://youtu.be/y7wFlQn5qTU
Yamaha PSR S900
https://youtu.be/ngdmHXnfMNM
Yamaha Tyros 4
https://youtu.be/8pQC6jGc5xQ
Yamaha Genos
https://youtu.be/RwBLCaBRcwY

Regards, Den.