I might pick one up

Bit of a debate, I may have 1-2 trips next year that will be more photo expedition oriented. I will want two bodies in action. I did not like flipping back to the 5DIV at Laguna Seca. So, my debate is R3 and get it early enough I can familiarize myself with it, or buy/rent a second R5. The 1DXIII does slip into the conversation, but when bouncing from one body to the other, having more similar between the two seems like a good thing.

As for the R1: I am not sure Canon is going to go the high MP/high FPS route others seem to think. For starters, that just feels more like Sony than Canon. When I think about an R1, releasing it with a global shutter, quadpixel AF, AF calcs 120 times per second (or higher), dual CFE card slots, etc just feels more like what Canon would do. 8K video spec is the big question that could drive the R1 to a high MP camera, IMO. If they do, there will be a sacrifice in terms of FPS. There will be a trade off. 30 MB for the R3 and 30 FPS is 900 MB/sec which is already ~2x the ~500 MB/sec CFE Type B cards are actually performing at. Unless Type B gets more efficient or Canon goes CFE Type C, they just are not going to be able to get much past that 900 MB/sec limitation with buffers allowing us to shoot 900-1200 MB/sec in bursts and the files write at ~500 MB/sec. So, I am expecting 15-20 FPS at high MP or lower MP and 30 FPS. Considering where the R3 was placed, I am thinking 40-45 MP and 20 FPS with Canon telling us "we talked to the Pros and for non-sports, 30 FPS was not necessary."

All that said, JW is getting great images with the 1D IV and MKI 500 f/4. So, you know, what do we really need?