OM-3 for Video / ProRes with Atomos Ninja / ProRes RAW ?

I'm getting close to convincing myself to pick-up my first OM body. Probably the main thing that's kept me from it in the past are the video specs. An OM-5 looks almost ideal to me, except for the 8-bit video. So, I'm looking at the OM-3.

Requirements are basically - good autofocus, 10bit video at least, 4k, semi-small set-up - om-3/s9 type body is fine, but no larger.

I'm mostly curious of autofocus experience. I don't need it for sports or anything crazy... mostly talking head stuff, but sometimes some movement, and I'd prefer something that doesn't hunt.

I can't find much in terms of reviews or uses on the OM-3 for video, or OM-1 for that matter. I found one video for setting up the OM-1 with an Atomos and getting to use Prores Raw. I happen to have a Ninja laying around, so it kind of interested me. But, the tutorial had them turn the camera to M mode... it made me wonder if that's normal and if the AF still worked? I assume it does, I've just never thought about shooting video in M mode.

TIA for anything !