Originally posted by PePe The difference in IQ and sharpness is noticeable only if you print in A2-size or larger.
The other thing is that I wouldn't want to have an all-new untested camera on a trip liike that.
I would agree with PePe - I travel a lot for my work, and would suggest that taking what you know is very good advice.
If you have a little money to spend could I suggest you purchase the HD DA 55-300 mm. It is an excellent zoom to travel with, and pretty light to carry in a bag. With the other two lenses you are planning to take that would cover the complete range of possible photography. There will be times when you will want a telephoto zoom.
My typical set up my travel day bag is 3 lenses with my K-3 - HD DA 20-40, HD DA 55-300, and a prime - usually the DA 15 Limited or DA 70 Limited depending on what I am planning to shoot. I used to have a DA*16-50 like you (it is an excellent lens for travel) but swapped it out for the HD DA 20-40 mainly to save weight, and also I found for my photography I didn't need the extra wide - and the DA 15 Limited could provide that when I needed it.
Enjoy your time in Japan.
Ross