Originally posted by Mattox yep, your all pretty much taking the words out of my mouth. Maybe because a lot of you feel the same way to. Thanks to those who have dropped into my website and have been able to see from my photos what I am taking about. The truth is i'd love for the 16-50 to be a full framer but sadly thats not the case, unless a great FF similar to that comes out plus the high resolution of the FF i may have to say goodbye
Even though I may still have a lust for a FF look, I am not sure if I like the D750, D810 or 5DMKIII etc. I would rather wait to see if Pentax will have any of the newer BSI sensors in the new models (APS-C or FF). I shoot events, so my requirements for better AF is likely more so than yours since the subjects don't usually pose and wait for me. But I find that my k-3 is more than adequate. The other thing also is the rendering of images in Pentax, from what I have seen so far, I am not sure if I like Canon sensor at all, for Nikon, may be, since they share similar sensors with Pentax from Sony. But I also don't find Nikon camera appealing to me in terms of button placement and ergonomics.
As for the 16-50 as it is... a lens designed for cropped sensor, it is very good for it does and the price is reasonable. However, if you upgrade to Pentax FF, you will likely need to get the 24-70/f2.8 anyway. If the new Pentax FF and 24-70/f2.8 cost about the same as the D750/D810 FX24-70/2.8, then I would still choose Pentax (probably new sensor and better ergonomics).