I first rented the 100-500, totally thinking I was going to buy it. Even had the money in hand. I also rented the 2X TC, and I already owned the 1.4 TC.
Well, I hated the 100-500. It was almost never long enough for the small to tiny, skittish birds I usually shoot, and it was a PITA with TC's, losing much of the zoom range, and having to take TC's on and off in the field.
Renting a 100-500 first, saved me a LOT of money !

I then rented the 200-800. Loved it so much, I ordered one of my own, even before returning the rental :)
I owned it for about 2 1/2 yrs, taking hundreds of thousands of shots with it, probably 80+% of which were at 800mm > on the crop body R7, for a 1280mm equivalent reach.

Finally, a few months ago, I bought my second 200-800, as its pretty much the only lens I want to use anyway.
Yes, I've seen the few 200-800's snapped in half, and in fact, one of those accounts was exactly why I finally pulled the trigger on my second one :) I mean, I always get the 4 yr extended warranties, AND I have personal items insurance specifically for each piece of my camera gear, no deductibles, full replacement cost. But that won't help me in the middle of one of my cross country birding trips, 2500 miles from home.

I know a lot of folks love their 100-500's, and I know they are fantastic lenses used for the right purposes. But a 100-500 and the 200-800 are just completely different tools.

Oh ! And BTW, the 200-800 is a "fantastic lens in LOW light" used correctly > always on a tripod, with a very slow shutter speeds allowing enough light to your sensor. I purposely wait for cloudy days. Direct sun "can be okay" if the sun is low, and right over your shoulder. Otherwise, I'd rather have clouds so I can shoot all day ;)

If you are after action shots, get a much faster prime lens, and a Full Frame camera. My choice for that would probably be a Nikon Z8 + PF 800 F6.3.
Fortunately for me, I'm into more "aesthetic" stills, than I am "cooler" action shots.

The images I get with the 100-500L glass is nothing short of amazing. It has a character

I have 200 - 800 on R7 and love this combination. I shoot mostly birds and reptiles trying to get some natural behaviours, so being able to keep some distance is advantage. I do not worry about iso much as I use dxo pure raw in post.

I have the 200-800mm and use it primarily for bird photography.  I love it!  I only struggle with it in low light when I have to push the ISO, but I can get rid of a lot of the noise in post, so I don't worry too much about pushing the ISO when necessary.   Great video.  I enjoy your content here in the US. Cheers!

I like both lenses. I use them for different things as I own them both.

I used the 200-800, but I switched to the 100-500 — it has better quality and sharpness, it’s lighter, and it has two focusing motors. In winter, I fell on ice; the 200-800 was in my backpack, and it just broke in half.

For my R5, I have a Canon EF 100–400mm f4.5–5.6L IS ii USM, an EF 400mm f4 DO IS ii USM and both 1.4x iii & 2x iii tele-extenders. For bird photography, I am curious to know how the RF 200–800mm F6.3–9 IS USM compares at 800mm to the EF 400mm f4 DO IS ii USM used with a 2x iii tele-extender. Ari Hazeghi got very good results with the latter combination, and I know Grant Atkinson likes that lens and regrets selling his copy. While the RF 600mm f4 L may still be the ultimate birding lens, it is big, heavy and expensive, and age is not in my favour.

Good video!
I do find the 200-800mm tempting but realistically atmospheric effects often limit the performance when you are using very long focal lengths.  I chose to get the 100-500mm because it fits the range I will mostly choose to use and it is smaller.
So I'm impressed by the 200-800mm but I'll stick with the 100-500mm.

I have both, and have noticed that in 200-800 the stabilization takes a bit longer to kick in. So for a short time when turning the camera on, it feels like there is no stabilization, but then it locks in and after that it is very stable. In 100-500 it is almost instant. But I really like 200-800 and if going for small birds, it is my choice always. Especially because I really dislike adding the 1.4x on 100-500 because of the resulting limited focal length. When the zoom is locked out due to the extender, it feels also more vulnerable to hits somehow. Anyway, for insects and generic daytime wildlife, 100-500 is a great choice, probably best. Thanks for the video as usual!

Good comparison. I was tempted when they announced the 200-800. I already had the 100-500, but the new one could be better for birds. Then I saw test shoots at TDP and learned that 100-500 with x14 TC @700mm has still better IQ than 200-800 without TC @800. So I desided it is not worth buying in my case. I'm very interested in the rumored 300-600 f5.6. If they indeed release such a lens and the IQ at least as good as 100-500 or better - I'll buy one.

I love my 200-800, again with the caveat that it requires decent light..often that mean the kind of light you want to be shooting in anyway. The 100-500 is a fantastic lens. It also needs decent light at the long end. It's 7.1 at 500mm. The 200-800 is 7.1 at 455mm (pretty comparable), then a third of a stop slower (f8) at 500 or 600mm. I would be shocked if the 100-500, which costs $1,000.00 more and is an L Series lens, was not a bit sharper, but whether or not it makes any real difference in a processed and printed image hanging on the wall, I'm not so sure. Though I rarely go there, zipping out to 800mm (without having to mess with a teleconverter) for something like a small bird is pretty awesome. I had both briefly, but sold the 100-500. Would love to see a 600 6.3 like everyone else seems to be coming out with!

I chosed the 100-500 because of the portability, sometimes I can't have my camera bag and a personal item on a plane, I have to choose, and I prefer a personal item and just throw the lense there and still have a useable backpack

Thanks for the comparison...for me, I had both, and side by side for mainly bird photography, the 100-500, even heavely cropped, has much better image quality 🤩, sold the 200-800

Dear Canon,we need some inexpensive professional grade telephoto primes like Sony just released. Their G Master 400mm f4.5 and 600mm 6.3 is something we need for the rf L series. We want a prime other than some ridiculous f11 or something in the price range of a car. Please 🙏🏾🙏🏾 get us some affordable L series telephoto primes

I chose the 100-500mm over the 200-800mm mainly because the atmospheric haze at 800mmm is sometimes an issue, and the 200-800mm is too large to walk around with. The 100-500mm is also the perfect lens for me to shoot with as I am walking to where I plan to set up my tripod to use my 500mm f4 or 300mm f2.8mm. That said, my girlfriend shoots with the 200-800mm on her R6 MKII and she loves it.

200 - 800 mm fits better with my mix of lenses. I’ll never go out with one camera body, so the 70 - 200 mm  easily covers the lower range and low light.  On the subject of low light, the 300 mm f2.8 is a beast. 200-800 mm is a winner for me.

I HAVE AN R7. 16-300 MM SIGMA LENS. WAS LOOKING BETWEEN RF 200-800 AND RF 100-500 MM... 200-800 ARE REPORTED TO BREAK IN HALF. please help to decide. will bw waiting for your reply.. p,s i shoot everything, from lanscape to wildlife and travel.

A few tips:
This video would have been way more interesting with you filming yourself out in the field and showing example photos to compare image quality, reach etc...

personally i think it'd be reasonable to get 200-800 + 70-200, even if I'd have to swap the glass.

Which one of these lens would you prefer to take on a safari to Tanzania, with the understanding you would bring a second lens to cover wider shots (e.g. RF24-105mm or RF70-200mm)?