Looks to have 20w amplifiers!!!
Hmmm. this could be the one!!
MSRP anyone?

And is the PX-350MWE just a white version of the classic PX-350?

Shouldn't the PX780 be compared to the PX850 and/or PX750 rather than the PX350?

Either way, what does it bring to the table that is not already present in the PX850 for example? An LCD and more buttons?

Edit: Hum, this is a slab?

Looks to me like it has all the auto-accomp features of the PX-350. In the past the only console keyboard with these facilities was the top of the range Celviano and now they have added a Privia which has this. The Celviano AP-650 has all these features too.

Does the PX-780 supersede the PX-850? Not really, it looks like a side step below. Hot damn, is that a PX-350 in the slim console design? Decisions decisions!!!

One thing is the 850 has 256 polyphony, 780 has "just" 128.
Looks like 780 lacks string and lid simulator. 850 has 18 tones, and 780 has 250 tones.

It looks exactly like the same 350 specs other than different speaker power

PX780 on left PX350 on right:

Physically from the pictures though, the 780 seems higher due to the speaker placement.
Not bad NAMM to me personally, as there will be 3 items I am trying out

If you did not think of it with the PX350 try to recall that, (as Mike Martin mentioned), you need to insert a jack in the headphone slot to trigger the boost in speaker output if it is identical to the PX350 in that regard.

The control panel faces the player rather than up.

I thought I pointed that out, but I didn't. I think I like that on the 780 actually.

Seems like it have midi unlike other cabinet models from casio.

Why does PX 850 dont have midi out?

Why most manufactures opt out midi when they add usb? Is that a big addition in electronics?

I just want control another keyboard with a DP, none of them have midi out; I was about to take 850,.
Now 780 have it, but I'm not interested in all the other bells n whistles

It looks exactly like the same 350 specs other than different speaker power

The PX-780 seems to be a replacement for the older PX-800 from a few years back. I think this model was a popular seller for Casio and had been discontinued when the PX-X30 series came out.

Yeah it makes you wonder sometimes what the manufacturers are thinking when they leave features like MIDI IN/OUT jacks off certain models. I guess the answer is it forces you to step up to another model to get that feature--that's modern day marketing. One other thing Casio could do better is make more replacement parts available for their pianos.

But PX 850 is the flagship Privia, still no midi in/out

Yes it is a step up model but not the highest step on the Privia line. The new PX-5S will cost more. I'm not sure why Casio does not include MIDI IN/OUT jacks on it. When the PX-830 was released, it seemed to replace the PX-800 although Casio took off the extra sounds/drum loops and accompaniment, and MIDI jacks the 800 had. It ended up a PX-130 in a cabinet with a bigger amp, speakers, and ivory touch keys. Not sure why they made these changes. The PX-780 seems now to be the replacement for the older PX-800 but it does not include the pedal bar, only the stand. The pedal bar is optional. Strange move for a $1299 MSRP.

Does a digital piano model like the PX780 attract many people who will use the 5-pin MIDI IN/OUT?

In this case keeping everything in the PX350 may have been the least trouble and expense.