That certainly looks like quite a marked lean. Out of interest:

Did you remember to turn off SR?
Did you check the viewfinder after the picture was taken, without touching the camera, to see if it was still aligned as expected?

I was going to suggest removing (very carefully) and refitting the focusing screen incase it's not properly aligned, but you've shown lean when levelled using the bottom of the viewfinder.

I've tested my GX10 on a tripod with a cable release and no SR matching lines with 4 lenses (one prime and 3 zooms) at ~200mm (I was actually testing the quality of the lenses) - no lean here.

If I don't use the cable release still with no SR - very slight lean on some. Conclusion for me, on my tests, pressing the shutter release makes the camera lean ever so slightly, depending on the force I apply on the shutter release.

WRT forum polls, they have no real statistical meaning with such few results. Firstly, you'd certainly need a sample in excess of 1000, then you'd need a truly random sample of pentax owners. This isn't random since people with a perceived problem are more likely to vote.

I purchased one of these from this seller for a few quid and it worked just fine. I had some issues using it with Macro work, so haven't been using it so much of late:
http://tinyurl.com/2rqo87

There's little difference between X1 and X2, but you'll probably notice a raft of changes from v8. One thing some do complain about is the speed of PSP, and I must say that it is slow. That can be quite annoying when you're making small adjustments with the full screen preview.

Other than that, I find the noise reduction and intuitive (to me anyway) interface of greatest benefit to me.

IIRC, installing the latest version placed it in a version specific directory and left the older version intact, so you should still be able to switch between the two.

Indeed. I couldn't fathom that. I also missed the ability to crop to my own desired dimensions before then resizing the image. Apparently both features (undo/redo and proper cropping) are coming in v5 of Bibble.

Well, I'll happily admit to using PSP (now upgraded to X2).

I've tried the others and this one fits my style of use and preferences and I'm very happy with the results I get from it.

I did play with Bibble for some time for RAW processing, but it exceeds my needs. I've also tried PS and PSE.

I can't justify the extortionate (IMHO) price of PS when I won't use 99% of its features where I can find 90%+ of the ones I need from software that costs a fraction of the price.

One thing I'd certainly say, PSP is very slow compared to, say, Bibble which is like lightening in comparison, but I'm patient enough

I doubt that it would make much difference. SR is intended to compensate for small movements in hand shake and only in the vertical plane. I would imagine you'd need high shutter speeds (and therefore fast glass) and/or a stabilisation system as you mentioned.

That's a nifty little site.

Now that made me laugh

I'd go with 1 also - focus is that bit sharper on and around the beak.

How do you find the weight of the 135-400mm Sigma? Do you always use a tripod or also use it hand-held? I had the 170-500mm Sigma and although it was possible to use it hand-held I found it difficult to get stability at the long length (understandably).

It was that guys site (plus a few others) that made me splash out on the 180mm macro.

I love my 50mm lens, but the longer lens does help get a lot of shots I wouldn't be able to get as close to with the light needed, in particular very small insects: