Okay, this is good! Between this and the new SX600, there are finally some signs of life at Yamaha, other than for their most expensive keyboards. However, based on the very basic information available, there doesn't seem to be that much different, other than the S.ArtLite voices. Don't get me wrong -- the addition of S.Art to a keyboard like this -- even a "lite" version of it -- sounds impressive. But it doesn't seem like much else has been added.
But, we'll see. If this, and the SX600, are any indication, my guess at the PSR-E473 upgrades will be the addition of S.ArtLite (can't imagine them putting it on the 300 series and not the 400), and perhaps portamento of some kind, because that is already on the PSR-I500 (and the Casios have it). Now, with the I500, just from reading the manual, it appears that there is no way to store the portamento settings in a registration, and turning it on and off requires going into a menu setting. I hope that is just an omission in the manual and that it can be stored in a registration, and likewise, if the E473 has portamento, I hope it can be stored in a registration there, as well. Otherwise, it is almost useless for live playing, because while you might want it for a synth lead, you certainly would not want it for a grand piano, and based on the manual for the I500, it looks very cumbersome to turn on and off in a live playing setting.