Hi Simon
I would say that they are both excellent keyboards, with little difference in the superb quality of their sounds.
The Korg got my vote for the following reasons. Build quality - it’s aluminium, not plastic like the Genos, coloured touchscreen, Korg’s free regularly updated styles and other free software, including operating software updates, Style Creator - allows you to create a style in seconds from a midi file, TC voice Helicon built in - allows voice manipulation, price.. I think it’s around £1500 cheaper than Genos. That’s a lot of money to save against a similar spec’d instrument I think.
I can’t answer your sequencer question I’m afraid, it’s not something I’ve used.
Having said that, I’ve read many times that there is nothing that can’t be done on the Korg if you know how. I think basically it’s a computer, I’m sure you’d feel right at home on it with your skills!
Korg have released many training videos for the PA4, again freely available on line.
Both fantastic instruments. Hard to imagine how keyboards could ever sound any better really than they do today.
Hope this helps a little.
Kind regards
Peter