I've always been dissatisfied with keyboards as replacements for pianos. None of the ones I've come across have had that feel of weight that's needed for someone who's played real pianos his whole life. We bought a Casio piano to use for the rehearsals of Grimhilda! back in 2012, and it was effective enough, but it lacked something. It hadn't been to to gym to build its muscles.
What I think it lacks, along with most keyboard pianos, is that sense of standing up to the strain of a pianist fighting to produce the right sounds. When it comes to something soft, keyboards aren't too bad, especially ones like the excellent Casio PX850. But when it comes to taking the full weight of a long-experienced pianist hammering at them, nothing beats a real piano, an instrument that stands up and takes a beating without whimpering. (Totally unconnected to this, why is wimp spelled without an 'h' when whimpering has one?)
A pianist at full throttle needs something that will not only give its all in terms of the music, but also won't buckle under pressure. The last thing you need is the feeling that your keyboard is trying to run away when you're giving it a fistful of fortissimo chords.