Squeak,

All the drumkits sound better, not because of changes to the DSP settings, but because the DSP are truely brand new processors. The effects quality and characteristics are much better and as a result I can imagine they just MUST have reprogrammed the DSP on nearly each and every sound.

I can't find any proof for this, but after hearing it, I'd put my money on the new Rock-kit being a brand new sampled one.
But then again, if they made it sound this good by tweaking the DSP's, I wouldn't mind that it's not "new".

Your question indirectly triggered some long had frustration of mine : people expecting new arranger/synth models to be all-new revolutionary stuff. I can't help sharing my opinion with you guys, I'm sorry for that...but it's cheaper than the shrink :-) So here it goes :

In the last twelve years orso the realism of synthetically generated "acoustic instruments" has made a huge,giant, larger-than-large leap. Right ?
Now compare Tyros3's breathy tenorsax with the 10 year old tenorsax the VL-1 gave us and the difference is not all that big anymore. The Virtual Acoustic Modelling technology didn't make it past that stage : it hasn't evolved, despite of being used in the VL-7, VL-70m and VL boards for the Motif XS and so on. On the contrary, the soundquality became worse and worse 'cause ever cheaper and less DSP's where used in an attempt to make this technology payable.
We, the arranger/synth customers, didn't embrase such radical technology and didn't want to pay the prices. I believe that VAM was lightyears ahead of it's time : it gave some analog-type of modelling and realism at a time when "digitallity" ruled. People didn't see it's worth and so the PCM (sample) technique is the only one to evolve to this day. I think we are approaching the limits : extreme costs in a growing number of samples per tone will definine that limit. That's the reason no new model of a synth/arranger or what so ever will be a "revolution" in the acoustic sounds department anymore. That's also the reason many manufacturers re-use samples/sounds and only 'tweak' them, because it's way too expensive to keep making new ones and the costs outweigh the improvements.
That's why I find the new DSP's a revolutionary improvement ; that's an area where they (Yamaha) still could make a lot of improvement.

i.m.o. most of the future instrument releases won't be a big improvement and upgrading will become more and more questionable as the new models will become loaded with "goodies" only there to tempt you to think it's a "revolution".

(PS : yes, I know Korg and Roland using "reed"-modelling, Virtual Acoustic Boards and so on, but they haven't by any mile approached the realism and soundquality of the VL and VX. They just copied part of the idea and there it seems to end. I also don't see/hear anything about large investments into R&D for these kinds of techniques from any of the major companies).