Even if it incorporates a true grand piano action; it's still different, at least to me. The simple psychological effect of going from an immense intrument (grand piano) to a smaller one (electric) must effect one's playing, or at least one's approach and manner of touching the keys.
A digital has significant advantages over an accoustic. You can take it and set it up anywhere, it has multiple voices (great for Bach!), you can play in silence or through any sound system, and you can record. I have a grand piano, but the digital is so versatile that I use it most of the time for practice.The touch and sound of many digitals is just fine, as is the touch and sound of many accoustics. One is not necessarily inferior to the other, they are simply different. Do not let the price differences fool you... you are paying for more expensive materials, much higher production time and transport cost with the accoustic. With high-end accoustics, you are also buying new mansions and Ferraris for the old farts who run the company.
One thing that must be said is the touch on all digital is very light
I don't know what expensive is, but I have seen 25 000$ Roland’s for sale.Everybody has made good points on both ends of the barrel.The quality of the new digitals is very impressive. Remember, it's computer technology. Change comes quick and what was terrible only 3 years ago is so much better today.You have to buy it for the reasons stated in the above posts, but make sure you get chances to play on the real thing. Although the gap is getting smaller, it is there and it is significant.I got rid of my upright and bought a digital and have never been happier. One, I have a small house and it takes less space. Two, I can play at midnight with earphones (huge) 3. It sounds better then my upright. The touch is not as good obviously.As long as you can still practice on the real thing once in a while, I don't think it can hurt you, the advantages are great.I would not recommend it some someone who is really really good however as they are for sure going to be disappointed.
You guys should all try the new digital pianos these days... pretty close to the real touch and sound of modern grands...and most got options you dont have on a grand