http://es.yamaha.com/es/products/musica ... e=overview
¿Puede hablar Inglés? Es más fácil para mí, para describirlo, en Inglés!
I was mentioning that there are many, many similarities between the YDP S-31 and the P-85, the latter being portable.
The keyboard action is Yamaha's GH hammer action which is responsive and realistic for the price range. The sound quality ( the realism of the piano samples) is quite good but I do find that the onboard speakers can be a bit of a let down. Remember that both the S-31 and the P-85 are built for either economy of space or weight for easy transport so many of the components will be smaller, specifically the speakers.
For the price range, either model is good but remember that they both belong in the "entry-level" range of instruments from Yamaha.