We have a 2023 850 XRS Renegade as well as a 2023 600R X Renegade. My wife and I are fairly aggressive riders.
Both of these are great sleds. Both are great engines. As many have stated, the 850 is very impressive power wise but can be a handful for many on tight, twisty trails. We ride in the Northwoods of Wisconsin (very tight, twisty) and I think the 600R is just as fast and easier to ride at speed on these trails. Once we head into the UP of Michigan where the trails are straighter and wider, the 850 really excels.
I think the answer to your question depends on the type of rider you are and the type of trails you ride. I can say that after roughly 3k miles this season on my first 850, I have concluded that for my riding style and our trail system, the 600R is plenty of sled for me.
Additional note : what is amazing to me about the 850 is the power it generates without gas or oil consumption penalties. Again we ride tight trails so there are very few long high speed pulls but my 850 sips oil and gas. Both engines (850 / 600R) consume the same amount of oil and gas when run the same way on the same trails.