I've got a Casio px 735, do you consider this to be a significant upgrade over the privia range?
You mean, if PX-S3000 is a significant upgrade?
Let's see.
The piano samples, although not recorded again, are probably improved. Similarly as in Kawai.
And, of course, the main piano remains the same, a Hamburg Steinway.
The AiR engine, responsible for playing piano sounds, has been improved. It could probably be called AiR 2.
For other instruments (700 instruments altogether) AiX engine is now used.
It is promoted as an important leap in terms of quality, realism and expressiveness of the sound.
And there is the new keyboard action. Which is controversial.
First, the length of already short keys reduced by 1/8 of an inch.
Second, instead of 3 sensors, only 2 sensors are used, although Casio claims their new 2-sensor solution is better than the previous 3-sensor solution.
Third, the black keys are lighter than white keys.
To me it looks perhaps like an advantage: the black keys are shorter (when all the keys are very short already) and they are higher located than white keys. So they require more effort to press. Making them lighter compensates for that, and evens out the required effort.
It is probably the best solution in the situation where there are no good solutions.
But not everybody likes that.
As to other things, there are more rhythms with a backup band, more melodic presets with chord progressions, added arpeggiator with 100 types of arpeggios / harmonizer.
But it seems that the rhythm editor and the melodic preset editor have been removed.
User rhythms and user melodic presets are no longer possible.
I hope I am wrong, but it seems to me that way.
And also it seems that, even though there are now more melodic presets, but the melodic preset for Autumn Leaves is now missing, unless it was renamed to some generic non-descriptive name. Previously it was named "Leaf". So it is missing and you cannot add it yourself. A double blow