This is just a cursory opinion based only on first glances:
Less polyphony-I know, it is used more efficiently.
no organ drawbars-just mix sliders
less styles-300 vs Audya 334(plus AJAM)
one mic output-vs 2
one line in-vs 2
no sub or aux outs-vs 4
Txt files ?
Plastic or metal case ? Weighs about three lbs less.

AJ said some time ago that the SD9 is not a replacement for the Audya. but the SD7. However, I am sure it is a great keyboard in many respects. I guess I am too old for the loopty loops they are pushing. I did see that CDG files are read. I use that on my Pa4X quite often.

Maybe AJ can give us a quantitative analysis and, whether they have ditched the veritable Audya.