I actually have a high quality digital (Yamaha N1). It even has the same action as a grand piano. Unfortunately, every time I went to my lessons to play on a real grand I had practically no control. The pedal especially is completely different on a real piano.

Also there are just so much more sounds you can produce on a real piano. I know it's weird since it's a percussive instrument but for whatever reason the way you hit the keys makes a difference.

I'm not a pianist but I can tell the difference between the best sampled piano synths and a real piano so there's no doubt a pianist can too. Of course it's better than nothing but a musician could prefer living far from work than not having a real piano at home.