[davidmanze]

Success is far from assured for them.  I can understand that the Pentax had their own "holy trinity" - the 31, 43 and 77 lenses - but they're all dated, screw-driven and question marks of various sizes hang over each of them in the optical quality department when dense digital sensors are involved (see PZ's own reviews - the 43 was especially woeful but the 77 wasn't very thrilling either; the 31 is pretty fine but it remains to be seen how good it is on FF where all the ugly edges are shown). Meanwhile, Sigma and Tamron have made strides in their design but their newest and bestest lenses are available for most mounts... though sometimes not Pentax anymore. So Pentax/Ricoh needs to act quickly and decisively, lest they be hit with the same stick as Sony a while ago: "Not enough lenses!"

  Yes all will be revealed with the Pentax FF body at the edges, but it may not be such a disappointment, the old Nikon AF-D series lenses in screw-drive are looking very good on the D750. (a thread to follow)

    I think there's somewhat of a misconception about FF sensors being demanding, yes they test a lens's performance at the edges, but there are having an easier time everywhere else, given a 30X20 cms print size it's the APSc sensor that tests the lens's resolution and struggles the most purely because of magnification. 

   My findings from the D750 and D7100 with the Tamron 150-600mm and the Nikon AF-S 70-300 VR both of which are only decent on APSc, are that they suddenly look more like quality lenses on FF.

    I think many will be pleasantly surprised by the results from some of this old Pentax glass, but even that obviously can't redeem the lack of modern designs.  

   I think if things go forward we will be seeing a lot more re-badged Tamrons!