Casio PX-410R

Extremely well designed keyboard. Primarily a digital piano, but also has many features of WK-series synthesizers. The manual is concise, yet adequate. I've almost never used it, the keyboard layout and menus are quite obivous and intuitive.
Selecting patches is rather dumb -- there are several dedicated buttons for some of the sounds (e.g. stereo piano, elec. piano, reed), other sounds are selected by entering their 3-digit number from the keypad or by hitting +/- buttons zillions of times - very annoying. Yamaha's dial control is much more convenient and probably more durable. However, you can store presets in custom slots and they will be remembered when the power is off. So there is a way around, if you plan to use only a few of the hundreds of sounds available.
There is a patch editor, called "synth". You can change Attack/Release, Filter Cutoff, Touch sensivity, Vibrato and DSP for the sound and the store it as a custom preset. The quality of lowpass filter is average (for a trained ear).
There are dedicated buttons for Grand Piano mode, Drawbar Organ mode and some other featured modes of operation, like SMF player.
There are also some cool features like mic input (karaoke) and two phone outputs. You can also switch second pedal function between 'sostenuto' and 'soft' mode, but this mode is not remembered after you turn off the power (strange).

Polyphony is 32, but for some of the sounds it is 16. The main piano patches and several other good-sounding patches all have 16-poly. Seems, that even with these limitations, you'll never loose the bass note with sustain pedal, but playing dense passages may result in slightly audible sound dropping (if you listen carefully). There are other piano patches with 32 poly, if you need them. But they are not stereo.
The keyboard action is very good. Velocity sensitive, graded hammer (or sort of). I am not a professional pianist, just an amateur, but even I can feel that it gives you good control over sound. By the way, this model has got an adjustable pitch wheel.
Also, PX-410R has an SD card slot, which is VERY convenient both for storing and playing back songs. You can even save a song as an ordinary SMF file (.mid). I also was able to use an MMC card instead of SD card.
MIDI in/out was a bad news to me. PX-410R does not have standard (classic) MIDI in/out, only USB MIDI combined in/out for use with a PC. Well midi is transmitted ok, but other things, like songs, styles, etc. are transmitted EXTREMELY slow. As for custom "wave"-sounds, forget it. 1) you can't make a real looping pattern (only whole-piece loop, which is useless), 2) you'll get mad while waiting for the wave tone to be uploaded into the keyboard, 3) the keyboard has only 4 MBytes of memory (for all custom data), so there is not enough space for hi-quality user patches.
The sequencer is OK, you've got 6 tracks, one of which can also hold accompainment. Re-recording the same track is rather inconvenient - you have to press the "song memory" button several times to get what you need. Also, when recording over an existing record, the previously recorded panel settings (mixer, effects, etc.) take precedence and you loose your current settings at the moment you press the "song memory" button. That's annoying since I have to store my current settings in a preset memory and then recall it just before I start recording the first track. Moreover, once you enter the record mode one more time, the DSP led goes off (why?) and it seems that you loose the default DSP for the sound.
Now for DSP - this is a GREAT feature of the keyboard. It can really do magic with the sounds, but you can have only one DSP preset at a time. So you can select several tracks and switch the DSP on for them, but this will be one and the same DSP preset. So, if you liked some synth bass sound and an say Mellow guitar sound, you won't be able to hear them together as ensemble - the latest DSP will override the previous one. And either the guitar gets the bass compression effect, or the bass gets the guitar mellow effect. Just keep this in mind when looking at the hundreds of sounds that this keyboard offers.
And yes, you can create your own rhytms (styles) out of MIDI files (you must use special software and a PC) and then upload them into the keyboard. I've tried creating a 80s hit style and that was a real fun.
Taking into account the keyboard's versatility, I'll still give it a 9 in this category.

Well, I owned a Casio CTK-671 keyboard, and this PX-410R is a huge step forward. Most of the sounds are much better, clearer, and obviously have higher resolution.
The main piano sounds are clear, most realistic when playing solo passages (with or without pedal), upper and lower octaves are very convincing, and the middle octave is good. Note that the internal reverb (which is on by default) adds some "metallic" flavor to the sounds. And if you don't like it, you can just switch the reverb off.
The drum sets are fantastic. You get almost every drum kit you can think of (several acoustic kits, power, electric, synth kits, jazz, brush, several hip hop and dance kits, orchestral kit). With the exception of an ethnic kit. Please note, that the drum patches have no velocity layers (if you're into that thing).
As for the other patches, dyno elec piano is very cool, some "front" elec guitars are good, saxes and other reed instruments have very much vibrato to them (this is typical for Casio - flutes and saxes often sound as if they are detuned). Some of the elec organs are usable. Church and chapel organ are pretty impressive.
Indeed, PX-410R has many interesting applications beside its grand piano mode. The built-in acoustic system is very good. You won't be able to tell where the sound comes from. For an acoustic piano and a GM-karaoke instrument it is more than enough.

I've owned this keyboard for a month and a half, so far no complaints.
It seems quite well built despite it is plastic. No start-up faults or other hardware glitches occurred (as was the case with CTK-671).
I'm using it with an X-shaped stand and two pedals. Everything's fine and I am quite satisfied with it.
I am not a gigging musician, and even if I was one, I would keep this keyboard in one place. It's quite heavy. You can carry it, but I won't call it portable.
Not giving it a rating just because I haven't used it for long yet.

I didn't have to call support. I don't think I'll ever need this.

If lost or stollen, I would really miss it.
I love the versatility of this keyboard, this is a very good and compact digital piano with a handful of additional features. It is perfect for personal practice, basic arranging, and idea generation.
Some patches are plain, others are good. Some are excellent.
If compared to any other digital piano in this price range, it outperforms them in flexibility and keyboard action.
What I really miss in this keyboard is well balanced and well looped reed sounds (saxes, accordions, and flutes), easy patch selection (sort of dial or something) and a classic MIDI interface (not USB).
As an overall rating I'd give the PX-410R an 8.