I am considering keeping the Sony A6400 camera and lens, but only if it checks out and I am satisfied enough. It is a used camera and lens. My sole reason for considering this Sony gear is to obtain a lighter and smaller system than my Pentax gear.
I have made a number of comparison images between the Pentax and Sony. The colors are different but I haven’t found anything significant color-wise that would make me reject the Sony. My biggest complaint with the Sony is that it is far more complex as far as the menu goes and it will take me a while to learn their system, but that shouldn’t be a problem. I have had years to learn the Pentax system and hopefully I can learn and adjust to the Sony system.
The biggest differences are the size, weight, and ruggedness. The Pentax K-3 III is more rugged and able to withstand being knocked about and used in the rain, snow, and mud. But the difference of most interest to me now is the difference in weight. The Pentax K-3 III with the Pentax 18-135mm lens weighs 1220g, while the Sony A6400 with the Sony 18-135mm lens weighs 730g.