The Tyros 2 will sound better in every respect to the PSR2100 like night and day.
The converted PA50/80 styles IMHO sound better on the Tyros 2 by a leaps and bounds as compared to their the onboard PA50/80. Not every style will be perfect, but most of them sound better on the T2, or T1 for that matter.
On the other hand, I still consider having a PSR2000 which I loved and a PA50 just for fun and the differences between the two. But I would keep the Tyros 2.
http://www.psrtutorial.com/Files/KB/KBother.html But don't take my word for it. Try it out, side by side if you can. Enjoy your Tyros 2
Scott
[This message has been edited by Scott Langholff (edited 07-28-2006).]