Lightweight and small and I give Sony a lot of credit for making such a lens. The price is reasonable as well. With that said, I much prefer the flexibility of the RF 100-300 mm f2.8 even though it weight considerably more. Bravo to both Canon and Sony for making excellent products.
Sure but Canon 24-105/2.8 + 100-300/2.8 cost about $4000 more than Sony 70-200/2.8 + 300/2.8.
BTW Sony 70-200/2.8 + 300/2.8 is still lighter (and cheaper) than Canon 100-300/2.8
The are designing it with different philosophy.
Canon is making it for professional in stadium that will position in a static spot, with tripod/monopod. And the focal length before 300mm gives so much flexibility in tracking sport subjects.
Sony is designing it for the one-man-army. Extreme weight saving for handheld with minimal accessories. However its usage is no different than traditional SLR/DSLR equivalent.
Whether you want to switch lenses or not. It's down to how you use it. Typical folks on internet are more likely to be one man enthusiast, so bias towards Sony as it seems better for their use...IRL international sporting events, I doubt you cannot find a RF100-300L.
What CaNiSo are all preparing for Olympics...Nikon focus on the Super-tele primes, Canon on zooms, and Sony is trimming the weight down to extreme. It's a great time to enjoy gears.