Strange how we have different needs and tastes. 12 of the things you listed have no interest to me and wouldn't make a difference. A few of them, such as the semi-weighted keys, 76 keys, no speakers and SA2 voices are even detrimental to my usage.
Knobs, sliders, bigger screen, Yes to them.
I've had dual players in my Korgs for 10 years or so and don't recall ever using more than one at a time, and actually very seldom at all.
If I were to choose between the 900 and the Genos, it would be a no-brainer for me.
Again, we each have different ways we use arrangers. I would seldom use the Ensemble, as great as it sounds. I don't care if there is more than a couple of good B3 organs. The 76 length means I have to change stands, change bags and arrange things differently when I move it.
I've never run out of memory on any of my arrangers, even Yamahas.
The speakers are not that important either way, but I'd just as soon have them as not.
Now, I totally understand why most people would prefer the Genos, just not me. And it costs quite a bit.
My Korg PA4X is ALMOST the perfect arranger for me, but I suppose we'll never have a perfect anything will we?