My own (similar) experience with A3+ prints from the Imaging Resource DNGs for the K-3 and the K-5IIs is that there is extra luminance noise and colour noise at high ISOs (I mainly used 51200) with the K-3. When I applied enough extra colour noise reduction to get that under control, I still had to apply extra luminance noise reduction to get that under control too. And the results never became as satisfactory as the K-5IIs. (I had a friend check the prints yesterday to make sure it wasn't just me).

(In all other respects so far, the K-3 is a better camera than the K-5IIs. It is faster in operation, for example 3-image bracketing appears much faster. But unless I find that I've been doing something wrong, or there is something wrong with the Imaging Resource DNGs, I'll probably use my K-5IIs rather than my K-3 for high ISO photography. I'm still testing this).

Thanks! I had better press the button to buy that new PC then.
This is what I am thinking of.

My K-3 versus K-5IIs tests simply printed the whole image at A3+. The subject matter was the same size in the frame in all cases, and a casual glance might have considered them to be the same photo.

In other words, I tested for a real-world situation, printing at my favourite size, eliminating any other debates about how to compare.

Precisely! High ISOs can be liberating, as extra options to be exploited as long as you can still get good results.

I have gone up to ISO 12,800 with my K-5IIs this year. With careful choice of parameters in Lightroom the results were very sharp, and the noise, while there, wasn't intrusive or objectionable. And with some trickery in Photoshop I could have reduced the noise even further.

Unfortunately, that agrees with my own assessment. I was hoping I was wrong. (But I think up to about ISO 6400 there is much more similarity between the K-5IIs and the K-3).

I will soon know. The latest Track & Trace for my K-3 reads:
31-10-2013 - 06:32 - Manchester Piccadilly Depot - Loaded to vehicle for delivery

Process 2010 was introduced with Lightroom 3, not 4. My understanding is that noise reduction, which was dramatically improved in Lightroom 3, is pretty much the same since then. (But the Basic panel was very much improved in Lightroom 4).

Yes, I will be upgrading to the latest versions of Lightroom and Photoshop when I have upgraded my Victorian-era Windows XP PC to something more recent! Thanks.

I'm still using Lightroom 3.6, and it handles the K-3 DNGs well. (In fact, it handles my K-5IIs DNGs well, even though it was released before the K-5IIs). My Lightroom is currently using the K-3's DNGs' embedded profiles.

I expect Adobe will eventually create their own camera profile for the K-3, but I never use Adobe profiles. I'll create my own for the K-3, just as I have for all my previous cameras.

I was comparing the K-3 at ISO 51,200 with the K-5IIS at ISO 51,200. The K-5IIs worked OK with the Lightroom default "Color" noise reduction value of 25, but the K-3 didn't.

When my K-3 arrives in a week or so I will have to experiment to get a feel for how hard I can push it within the range that Lightroom can handle. My K-5IIs will become my back-up camera, always reasonably accessible, so if the K-3 turns out not to be as good in this case as the K-5IIs I won't be too upset, because I will have the latter to fall back on. But I would obviously prefer to be able to stick with just my K-3.

I've printed the IR ISO 51200 K-3 DNG and the corresponding K-5IIs DNG at A3+. I first gave them both the same Lightroom noise parameters: Luminance 50, Colour 25. (No sharpening). The K-5IIs print was OK, although noisy. The K-3 print was dreadful (colour noise mostly).

I had to increase the K-3 noise parameters to Luminance 75, Colour 50, before there was approximate equivalence of print quality.

I don't know whether such different parameters should be expected, but the Lightroom default for Colour is 25, and that is normally enough.

Up to about ISO 6400 I don't think there is much difference between the K-3 and the K-5IIs. Above that things diverge.

Thanks for that.

In effect, the effect will be evenly distributed across the sensor if the shutter exposes the sensor for an exact multiple of the vibration period. If there are multiple vibrations per exposure, any difference caused by one incomplete vibration is likely to be insignificant.

(I wonder if I should say "an exact multiple of half the vibration period"? If the vibration is symmetrical, half a vibration should do the trick).

The IR article quotes Ricoh/Pentax as "fully functional up to 1/1000th second". That presumably excludes "fully functional" for studio flash. It will be interesting to see what "partially functional" means for studio flash. But this is a separate matter - unlike shutter-based exposure, flash-exposure presumably acts evenly over the whole sensor.