If a 16 meg piano sounds ok to you, use it. if a 16 gig piano sounds good to you, use it. Bigger isn't always better, but bigger is often better. Good programming is also important. Poor programming with huge amounts of samples probably won't be as good as great programming with smaller sample size.

But, a piano played softly sounds much different than a piano played loudly, and it is more than just something that can be emulated with filters. So using 1 layer and filtering it for dynamics doesn't sound as real as multiple velocity layers. Unless of course the velocity layers are poorly programmed and there are severe jumps from one layer to the next which makes playability difficult.

Finally, if large numbers of people here are duped into believing that Chet Atkins and Tommy Emmanuel are great keyboard emulations of guitar, who really cares what those same people think about the sounds of various pianos. Decide it for yourself.