Dear Pentax,
what happened when you designed the D-BG5?
It is absolutely necessary that my right thumb finds the buttons without my head thinking about it.
Yet, on the D-BG5 the AF button position is different to where it is on the K-3. That is an ergonomic catastrophe, AFAIC. I love my D-BG4 on my K-5 II but cannot imagine to ever be not frustrated about the D-BG-5 forcing me to be conscious about which way I'm holding my camera.
Are you planning to alleviate this issue through making grip and/or camera buttons customisable? If you allowed swapping the functions of the green button and the AF button on the K-3 or the AF and the AE-L button on the grip that would help.