It seems that a few people have had their hands on a pre-production R1.

Jan Wegener is one. Solid review. Long story short, he mentioned making the R1 his primary camera with the R5 II secondary when he needs more resolution. Cited better AF, apparent better DR, great colors, great EVF and being able to use the AF-On button to go from 20 fps (half press) to 40 fps (full press). Calls it the best overall camera he has ever used. Cons were the 24 MP and buffer size. But those were minor-ish cons for special situations.

I also have seen this video from Fabian Fopp. I had never seen a video of his before, but apparently a wildlife photographer noteworthy enough for Canon to give a pre-production model too. He was also a fan.

As for me, I actually pre-ordered an R5 II and R1 at the time they were announced. The R1 pre-order was more of a "why not." As I have mentioned in the thread of the R5 II, I canceled that pre-order as I was simply not excited enough about the R5 II over the R5.

But....I have never canceled the R1 pre-order and the excitement over owning a R1 has grown. I am definitely going to keep the pre-order and give it a go. I have anticipated going to a 2 body kit and had been thinking of having 2 of the same or very similar bodies. But, at this time, I am thinking I may end up 50/50 ish split between my R5 and R1. We'll see.