Okay, I'm a man obsessed. I've been checking out the online manuals of all of these new keyboards -- the PSR-E473/EW425, and the Casio CTS-500 and CTS-1000V. By the way, the manuals for the Casios are more than 300 pages long! But to be fair, all the information that Yamaha puts in a separate data-list document is included in the main manual for the Casios.
I've come to realize some possibly important limitations concerning the Casios. Keep in mind -- again, these manuals are BIG -- that I might have missed something, so if anyone sees that I've made an error, please let me know.
One thing is that the control panel for the Casios is almost too simplified, in that most functions are handled by the 5 soft-keys under the display. This includes the registrations and the style control, which would each have to be called up separately. The problem there is that, if you're playing a song and want to be able to do drum fill-ins and transitions to style variations, you can do that, but you have to have the style menu displayed. But if you then want to switch registrations during the song, you now have to go through extra keystrokes to call up the registration menu before you can switch registrations. This could be a bit cumbersome during live play. The E473/EW425 have dedicated buttons for styles and registrations, as has been the case for the previous versions of the E400 series.
Beyond that, to change registration banks on the Casio, you have to turn a knob -- which could make it a little more difficult to "land on" the exact bank you want during live playing. With the Yamaha, as before, you can just hit the bank select button, and then -- I believe -- just hit a number key for the bank. I say "I believe" because the Yamahas now do not have a dedicated numeric keypad. However, the voice/style category buttons can act as a numeric keypad, and when I read the manual, that seems to be the default for those buttons (for them to be numeric) unless you are selecting voices or styles. With voices and styles, the category buttons default to the listed categories, and you have to hit "shift" "numlock" to select voices and styles numerically.
I previously mentioned in another thread that the CTS-1000V allows you to make custom voices, but as I read the manual, it seems that these voices are only related to the vocal synthesizer. I'm still not sure exactly what they do -- they could be custom user slots for different sets of lyrics. And to this end, yes, the Casios do have filter and envelope controls that can be accessed by the assignable knobs, in a similar way to the Yamahas. But nothing I could find in the Casio manuals indicates that the filter and envelope settings that you dial-in can be saved to a registration! When I looked at what CAN be saved to registrations, it mentions what the knobs are assigned to do, as well as the part they are assigned for (it does seem that the knobs can be used for more than just the upper/right side of the split keyboard, which is nice) -- but nothing about saving the actual parameter values of those knobs.
If you're looking to create custom sounds/patches in a synth-type fashion, then not being able to save the filter and envelope settings to a voice or registration is a serious limitation. I'll really have to get my hands on one of these keyboards to see if this is the case. On the other hand, the Casios have dozens of DSP effects, some involving filter-type sounds (like "wah" effects), that can be saved to a registration. And there are a variety of detailed parameters of the DSP effects that can be edited. Of particular interest is, on the rotary speaker effects, you can save the acceleration speeds from fast rotary to slow rotary -- but without there being a dedicated button for rotary speed, I'm not sure how this is used. I might also mention that a Casio I have that I bought in 2003 has DSP with similar parameters, and again, I never understood how they are used with that keyboard, either.
Speaking of DSP, an advantage of the Yamahas is the fact that there are two separate DSP "channels" where one affects the main voice, and the other can be set to affect the entire keyboard or to any specific part, including the style and drums. This second DSP channel that can be set to different parts of the keyboard has fewer DSP options, but this is still a nice feature.
Finally, I had mentioned that in one of the videos for the Yamahas, there is a dynamic rotary speaker speed-up or fade in effect. I'm still not sure how that is done, but I have a theory. With the S.Art Lite button, if you use it with a non-S.Art Lite voice, the manual says you will get modulation. As I did not see any S.Art Lite organ voices listed, maybe the modulation for the organ voices is a rotary speaker effect, and perhaps the keyboard player was engaging this by way of a pedal set to activate S.Art Lite. Additionally, the manual lists some organ voices in an unusual way -- something like "Jazz Organ + Fast Rotary". They way it lists it with the plus sign, instead of just saying something like "Fast Rotary Jazz Organ" makes me thing that this is implying some sort of built in effect, and perhaps this is a part of that Leslie/rotary effect in that video.