Originally Posted by little laker 
I've seen some stunning results from this lens.
However I'm wondering why Pentax hasn't told Tokina to either fix the issues, or just shove it
I think after the merger (and therefore, after gaining the rights to SDM technology,) Hoya wanted to crank out some Pentax SDM gear as fast as possible. I'm hoping to do a massive upgrade soon, and would like to buy Pentax over a third-party alternative.
It's a shame, really, and not a good look for Pentax. First impressions, as Lynx tells me, last. Maybe it wasn't selling too well under the Tokina badge, because of the problems, and they slapped the Pentax label on there to expedite things. And maybe Tokina's nowhere near as good as Pentax. Granted, they do make that 35mm Macro, but maybe that was in collaboration with Pentax, and the 16-50 wasn't.
I'm hoping to get this lens for a job I'm going for (I hope I get it!) but I don't want to have to tell the boss, "Yeah, like I said, I could supply my gear, except I've had to send half of it back because the main lens I'm using was busted when they made it."