Tough choice to replace the 1Dx and EF 85 1.2L II. Greatest camera/lens in my previous EF arsenal. Now onto the next chapter with the RF equivalent.
While I don't doubt it's a great performing lens, it needs lots of light, and yes, it does AF almost instantly when it finds contrast on a subject in areas lit with the light of one bulb. When it does have the light it needs, lightning quick, and much faster than the EF on an EF mount camera. The control ring EF to RF adapter worked really well, so, if you're in the market for a used EF 85 1.2L or 1.2L II, just know it'll perform light years ahead on an RF mount body. I've put that combo through a fair test, and it met most of my expectations. I did not like the control ring being on the back, so, I chose the RF version for the next 10 years.
Yes, it's heavy, but, I love that about it. My camera has a grip, and I will (most likely) use this lens in portrait orientation 99% of the time. I love having a shutter button in that orientation (and will most likely acquire a pro body in the future for that sole reason). The R, grip/batteries, and lens are overall a bit lighter than a 1Dx and EF 85 1.2L II. I just 'feel' it and don't really care what the numbers dictate, but, I'm sure they'll state the same (loved that combo by the way, despite the weight).
The top corners are dark as that's where the light falls off at the garage corner/walls and is no indication of 'any' kind of vignette caused by the lens. The lens is sharp, big, has a shorter MFD than the EF lens, larger diameter, weighs about 100 grams (or so) more and has been a pleasure to use, thus far.
The forum uploader applies it's own sharpening which I don't believe can be turned off. I currently have it set to 'low' when uploading...but, wish I could turn it off. Anyhow, enough babbling, here's a FF image, in exchange for a pool noodle battle. Both parties were happy. 
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