Experience with Lumix S5ii and Sigma ART 18-35 1.8? Which adapter do you use and how are the AF results?

Hi all,

I'm in the process of jumping ship from Fuji to Panasonic and ordered a Lumix S5ii. I was thinking of selling my trusty workhorse Sigma 18-35 1.8, but when I tried the camera in-store I saw you can choose to crop in to APS-C in all video modes. This is pretty cool, because the APS-C crop is still true 4K (if I'm correct?).

I saw you get way better rolling shutter performance i APS-C, twice as good(!), which is super nice since I film quite a bit of action sports. I think I'll use this feature quite a bit and that made me rethink my intention to sell the 18-35. Does anyone have any experience with this lens on the S5ii? Which adapter do you use? My Sigma has an EF mount. And how's the AF performance with that adapter?

Love to hear, thanks!