Yeah I am using the RS3! It is beyond compatible, works perfectly even when I am quick adjusting balance after lens swaps and don't get it perfect. This wedding was outdoors in direct sunlight while also being over 90 degrees out and both A7iv's worked perfectly, I was nervous because of the reports of overheating but we had no issues at all. We were shooting in 4k XAVCS and did not overheat. I wouldn't stress too much about the overheating but I still try to avoid sketchy situations if possible just out of paranoia.

Thank you so much!