I was thinking of putting together a light weight kit for events where the client wants a montage of people coming in, mingling etc. There's a relatively in expensive motorized gimbal called Zhiyun Crane M for $500 paired with the Sony A6000 $400 with prime 16mm 2.8 or the standard kit lens.

I own a 70d but I'd have to get an expensive prime to be wide enough to work in crowded events, and to get it under the 2.6lbs payload limit and it still be heavy. My 17-55 is too heavy and big for this gimbal.

That's why I think the a6000 would be ideal for quick run and gun without the shakey cam as long as it can handle indoor low light. I thought about the A7S but it gets heavy and expensive with wide prime.

Anyone here use a mirrorless camera gimbal setup?

What about the Zhiyun Crane, should meet your needs?

I don't have any experience with the A6000, so my questions won't be directly addressed at what you are asking.
I also have the Canon 17-55 f2.8 and yes it is too heavy to use easily on even a larger non-motorized stabilizer (for me anyway).
Is f3.5 maximum aperture on the wide end not fast enough for the lighting you'll be shooting in?
There are currently 3 lighter weight Canon wide angle lenses of 18mm or less that all have a maximum aperture of f3.5.
The 10-18 IS STM, the 18-55 IS STM and the regular 18-55 IS II.
If you really do need f2.8 at very wide angle and at absolute minimum weight, then I think some type of mirrorless would be the choice.
I will add that I have been very pleased with the video performance of my Nikon D5500. It is much smaller, lighter and cleaner than any of my Canon dSLR's. The 18-55 VR II kit lens is limited to f3.5 on the wide angle, but it is also smaller and lighter than the matching Canon lenses.
The articulated touch-screen and the 60p 1920x1080 have been very pleasing, and it is much easier to use on a regular stabilizer. I also know it is slightly below the weight maximum for some motorized stabilizers, but I haven't obtained one of those yet.

Sony 10-18 f/4 with the CAME-TV Single or Optimus.