For the amount I print (little) it is simply not viable to print at home. It ends up costing far more in terms of ink and maintenance.

Loxley Colour have excellent service, high quality printing, and quick turn around. I have put prints from them into gallery situations, with no worries.

Don't believe it. That is a company with a vested interest in showing how good their process is. Their images seem excessively manipulated. Please refer to the Luminous Landscapes review already posted, as they are a more trustworthy source and show a more modest improvement. (Though still a worthwhile one, IMO.)

That comparison in the link looks highly suspect to me, given that the shots were made on different days, etc.

However, there is no doubt that a weaker AA filter improves the resolution of an image; after all, it is added specifically to blur. The only comparison I have done is with two successive generations of the same sensor where the only significant difference in the camera engines was a weaker AA filter (still present, but less blur). The effect was like removing a thin gauze from the image; everything looked crisper. Sort of like doing a sub-pixel USM.

However, one cannot extrapolate except in a general sense. Every sensor and AA combination will be different. We can only await actual K-5 II comparisons.

ADDENDUM:
Here is a test from a trusted source, Luminous Landscape: D800 versus D800e. The "e" model has a small but significant increase in resolution. I know which I would buy (hypothetical universe).

I realise you are winking but I am not sure why. So I only ask you to re-read what I actually wrote, especially the word "apparently".

This is wrong on two counts: factual and ethical.

First, not all products fail equally. SDM lenses can and do fail. Screw focus lenses don't and apparently DC don't either. Pentax have acknowledged (only unofficially) an engineering defect with SDM which they then corrected sometime in 2012. Pentax have charged customers for fixes that should have been made without charge.

Second, the argument from the fact that the majority do not have problems is a head-in-the-sand attitude. Are you really saying we should ignore the issues because 51% of the products have not failed? How about showing solidarity with those Pentax users who have had problems, instead of siding with the mega-corporation? Companies count on this sort of fanboy behaviour so they can avoid their moral and legal obligations.

I wonder why this has become an issue in this thread? All I did was advise the OP to find lenses made in 2012. Do people really think this is bad advice?

If you buy a lens from 2012 on, they have been redesigned so that SDM problems are fixed. The problem when buying used is to be sure you don't get stuck with a potential lemon. I believe the US Pentax forum has a serial number database to aid in purchases.

All companies have manufacturing problems and bad products. It's how they deal with them that reflects on their integrity. Pentax were very slow to fix the SDM problem and still have never officially acknowledged what all Pentax users know. This is terribly unprofessional.

Well, maybe you're proving my point that "it is still largely going to appeal to current Pentax users".

Besides, it's still got only the 11 point focus system. I wouldn't expect more than an incremental change in performance. The main deal is the IIS IMO. Why don't you get that one and then I can try it out?

Point of fact: you have chosen to compare with the largest possible MFT camera. I would rather compare the K-5 II to the OMD E-M5, a camera with features the Panasonic lacks (IBIS) but which weighs about half as much as the Pentax! This difference in everyday use is significant.

As you can see here.

Hey, no I didn't say that! In fact, over the years I have been a strong dissenter from all the FF mania. Not because I have any problem with a larger sensor, far from it. But because I tire of all of those wish-on-a-star posts that read every little hint as meaning FF is around the corner. That's simply rubbish! Pentax never have said anything except that they support APS-C.

I have always recommended that people who want FF simply buy a Nikon. You're not going to do better than that!

I made the same decision some years ago, but the advent of micro four-thirds changes things. Have you considered an E-M5 and maintaining some compatibility with the system you have? Despite the naysayers who haven't tried it, Olympus glass is top-notch, and the line-up is quite impressive.

The same is true for Pentax, which has good fast glass in the longer end, but not the shorter. Their highest class of glass is weather-sealed and looks like this (with some indicative used prices):

DA* 16-50mm f/2.8 ED AL (IF) SDM = £600
DA* 50-135mm f/2.8 ED (IF) SDM = £600
DA* 60-250mm f/4 ED SDM = £775

I do not like the 16-50 as it has too much distortion and poor borders. Not to mention SDM failures. The two longer lenses render very nicely (though I have never owned them). On the cheaper side are three lenses that really punch above their weight, but are of necessity slower and not weather-sealed.

DA 16-45mm f/4 J ED AL = £200
DA 17-70mm f/4 ED AL [IF] SDM = £250
DA 55-300mm f/4.0-5.8 ED = £200

There are cheaper lenses yet, but I wouldn't recommend them.

So really it depends on what you are looking for.