I have both the 18-105 and the 28-135. I can confirm that the 18-105 distortion does indeed appear again when in 4K and 4K S&Q. Thanks for the heads up!
I have the Sony SELP 18-105. I opted for that lens as opposed to the kit lens which is cost 3 times more and is kind of clunky. The kid lens doesn't seem to be any sharper, at least not in my tests.
Can't speak to 4k but there seems to be a professional opinion the SELP is NOT at all suited for 4k.
I only use the 18-105 on jib work, when I can't get to the lens and need glass that communicates with the camera. It's good enough for that purpose. The rest of the time it's either in my bag or I sometimes mount it on my A7s. For $600 it serves a purpose and for that amount, it can be at the ready.
My main glass are Nikons.