Thank you guys for all of your replies! I ended up buying the Kawai ES110 after an intense week of basically reading every review there is to find online of the best digital piano under 1000 dollars. I read reviews and watched about 200 videos on YouTube, comparing the Roland FP-10 (my choice at first), FP-30, Kawai ES110 and then Casio PX-S1000.
At first, I liked the sound and the pricepoint of Roland FP-10 for around 400-450 dollars, but when I realized that just 'a few dollars more' could give me something special, I knew I had to look closer at the Kawai as it has been named by many as the best digital piano you can find for under 1000 dollars, since it came two years ago and still going strong. The Roland-models are quite nice and I played the FP-30 but was not a fan of the keys at all. And the sound is bright, metallic and a bit exaggerated.
The new Casio-models made me a bit uncertain of my choice to pick the Kawai, for a few reasons but mainly being new models and maybe offering something new in terms of connectivity, sounds etc as ES110 has been out for two years. But while the Casio models offered some neat features like running on battery, having bluetooth audio and being portable, it wasn't really important to me as I would mostly stay at home practising anyway. And it's not that hard to just listen to music on other devices. Audio-IN could have been an argument for me but the Casio seem to be missing that too? The sound was more than fine on the Casio but there was just something genuine about the sound of the Kawai that gave me goose bumps. I have never owned a DP before but it was obvious when listening to people play it that Kawai know how to make pianos.
The grand piano sound is fantastic, the speakers are more than enough for an apartment, and I absolutely love the key action and the way they just 'pops' back up. The feel of the keys are very nice and I like it better than Roland's ivory feel.
Very happy with this purchase, especially as I got it for just 450 dollars (it had been on display at a store for a year with a few people playing on it, but it was as good as new and everything intact).
I know that Kawai will most likely release the ES120 in the beginning of next year, but I'm not really missing many functions and it will probably be more expensive than the current ES110. A few more sounds would have been welcomed, or a display as it is quite tricky to change stuff. But with Midi (and being able to convert to USB by buying a cable), line-out and a fantastic key action, there's not a lot more to ask for so I can highly recommend it for anyone who's thinking of buying a DP in this price range.
As mentioned earlier, the only thing that could have made it even better would have been to be able to use instrument sounds from a DAW (FL Studio) and get the sound out of the Kawai speakers. It would have been fun to play drums on the keys but I guess this can't be done? Someone mentioned a "hardware sound module", how does that work?
Thanks again for all replies