I am not an expert in that topic, but I personally do not like pure sampled pianos (demoed several VSTs, on DP side Yamaha) nor pure synthetic pianos (Pianoteq, on DP side Roland). I have found that I like "hybrid" sound more (TruePianos, on DP side Kawai). At least as a solo instrument (Pianoteq is definitively simpler to combine with other instruments).
On pianoworld.com forum there are many discussions with technical details about advantages and disadvantages of different approaches, including the reason for quite "fanny" size of samples even on modern DPs. I mean for multi-voice acoustic instruments the size of samples is not a guarantee of success, in some aspects that is directly generating troubles instead of "perfect imitation".