Having tried the CLP885, you're right, it is primarily focused on the sound reproduction. The crossovers are perfect now; seamless from lows to highs. People who find Yamaha's typical piano sound too bright and cutting, will love this, but I kind of missed the ultra high frequency top end. But most people won't. It's a very comfortable, immersive sound experience. Speakers no longer all pointed in 1 direction either.
On paper, there isn't much difference, no. But once you try it, it *is* a different experience. However, I didn't get a chance to try it on headphones, where I suspect the difference would be slight, if even discernable.
There *is* another very big difference, but I'm not sure how you market this: instead of using the 2nd and 3rd contact points as the key-on velocity detection, it now uses the 1 & 2. (it still uses the 3rd and 2nd to detect key off for fast repeats, but with the 1 & 2 being used for initial velocity, you can play faster, especially noticeable on key repeats and when you're playing pianissimo.
If *you* upgraded from CSP170 to CLP785/885, you'd likely miss the CVP705 sound library & styles that the CSP170 uses (or maybe not, since you already have a Genos). But if you were looking at *just* the piano, the CLP685/785/885 all blow away the CSP170/CVP705 cfx piano sample, and additionally all 3 CLPx85's use the longer 25cm grand key (vs the upright style of the CSP170), and now with the new key on/off algorithm of the 885, it's much more responsive to play.
But the differences are still really subtle, yes. Even going back to the CLP585, the biggest fault with that was the crossover was poorly done (way to "thuddy" sounding) but the actual sample and key touch were already really good.
