I borrowed a few piano libraries, ArtVista Virtual Grand, Eastwest Boesendorfer, The Grand 2 and Akoustik Piano and tried them against my Roland Fantom X6 with the stock pianosounds.
I must say that the ArtVista is the best software virtual piano experience of all above mentioned that I've used. And it was pretty easy on the RAM too, about 250mb. The others where huge resourcehogs, like 1-2 gig of RAM usage and took ages to load...at least compared to the Roland synth
If you get the chance, check out ArtVista. You may like it alot.
For me it's not all about the sound quality though, it's about the playability. And that's where the Roland in my case really shines. It's within one single unit, fast loading times and plays really well. The sounds really sticks out in LIVE situations and on recordings, where many large piano libraries wouldn't.
AND since the Motif XS is like 2007 and the Fantom X is 2004 (I think), it wouldn't be surpricing if the Motif sounded better.
Good Luck
