I own both the lenses, just received my 12-60 a week ago. Long story short: the 12-40 is going away.
I had an EM5 II with the 12-40 and I was happy for still (using flash indoor), but got very disappointed with video quality (a body proble). The 12-40 is unbalanced on the EM5 II, too front heavy for me. I had to add the optional grip.
Then I got a g85, superhappy with video (and still) quality with both the 12-40 and the 14-140 (dual is2 is great), but the reach of yhe 12-40 was not enough for everyday use, and I was often preferring the 35-100 (an other great lens).
I gave it a go at this new panaleica, and I am definitely satisfied with it. Same quality, longer reach, much better balanced (even on the EM5II), same size, but so much better at video. The zoom ring is supersmooth, the aperture change is unnoticable in video.
the 12-60 feels less like a tank, but is very well built. The only thing I personally don't like is the colder colors with respect to the 12-40. But it is fixable somehow with in camera processing.
Ot really depends on what you need, but for me the 12-60 is a clear winner, and with dual is2 it is going to stay glued to the g85.