I happened across the review last night (or earlier this morning) as it was just posted and I was going to bed. Most of the comments beg the question about copy variation, QC standards, testing approaches - what ever, but Pentax, and all the other camera/lens manufacturers aren't providing any additional information.
Cameraville appears to be one of the few that actually buy$ their own len$e$, as opposed to getting loaners. Lens Rentals also buys theirs, but to rent out, so they do have (the need for) multiple copies that enable them to actually look at sample variations across the various brands. It would be nice if Cameraville (or anyone else, who) could score a couple of additional loaners from B&H, Adorama, Amazon, Pentax - whomever, in order to take a look at copy variation. That said, Lens Rentals is the only one (out side of the manufacturers themselves) who has the capital ($100K+), need, and interest to have (access to) the testing instrumentation (along with the testing expertise on the instrumentation) to actually quantify the copy variation.
One would hope that Pentax is occasionally looking here and over at Cameraville (appears to be pretty much the only other site) that does any reasonable level of reviews and comparisons of Pentax products.
So, does Tamron cherry pick, luck of the draw, sample/copy variation, level of Pentax QC inspection (rejection rate) and their QC standards/acceptable sample variation standards? I just saw that one comment as interesting speculation, one poster's opinion. Within QC standards? Acceptable image quality? With in copy variation standards? I don't know -
I would think that if this lens is sufficiently important enough to Ricoh and the Pentax brand/reputation, that some level of corporate interest would/might be expended on the topic.