I've got the older 100-400 f4.5-5.6 and am considering upgrading to the new one after handling it in a local camera shop but the size definitely has me concerned. I typically carry two Alpha bodies with grips, a 24-105 & 100-400, a 50 1.2, and a flash in the smaller international carryon Think Tank Airport roller.
Has anyone who purchased the new lens had issues with packing it in the cases you already owned such as a rolling carryon style camera case (Think Tank Airport series, Tenba Roadie, Pelican)? My main concern is if I have to pack in a backpack that I'd have a difficult time finding a backpack to carry it around in along with the rest of my kit.
In the luggage I use tubular padded lens cases. I've packed numerous 100-400/5.6 lenses; there are numerous cases of that size. I also packed the 200-600/6.3 in a tubular padded lens case without any issues. I'd have to check, but isn't the 100-400/4.5 even smaller than the 200-600?
One body with a 100-500 (same size as 100-400/5.6) and a second body with 200-600/6.3 fit in my Airportly Antidote last version easily along with a 24-105/4. I don't use any pouches in the photo backpacks, but in non-photo bags, like computer style, I use the wraps (Tenba is the best padded). https://www.bhphotovideo.com/c/product/1374647-REG/tenba_636_332_tools_16_protective_wrap.html