Listening to the Synth demos you've linked Olivier. The Steinway is interesting, and I like the choice of classical pieces. The sound is very dry but very accurate. My initial criticism of the sound might be that it's just a bit monotone. A bit nasal. Not much subtleness. Perhaps more layers are needed.
Actually, listening to more demos of the Steinway. It's really VERY impressive. I would definitely check this one out, folks. Definitely.
Listening A LOT to these demos. The Bos I don't like, although for a dry recorded Bos it's pretty spot on. (I just don't like them recorded dry.) But the Yamaha is excellent. It's the first Yamaha sample I've heard that I like.