Let's goooooooooooooo!
I've used the EF180L extensively this summer on both the R7 and R8, both for stills and video. For smaller dragonflies and regular sized damselflies I'd like a bit more magnification, the 1.4:1 of the RF100L is great on full frame, but the working distance isn't well suited to warmed up dragonflies. The 2:1 180mm variant would be an awesome replacement.
I immensely enjoy the 1:3 of the RF100-500L, the 1.2m working distance is a good compromise. Due to focus breathing it's a 300-ish mm lens at MFD, so that 300mm F4 variant looks very interesting! I'd likely keep the EF180L, I routinely run out of space when trying to photograph insects and amphibians in or near water. Maybe I should 'invest' in a pair of waders
And as
@Besisika said: 8k for macro would be awesome, the handful of experiments I did with my R5 with 8k had impressive detail and turned into great 4k output. My Intel CPU iMac did not like that, however.
R7 + EF180L on a tripod:
www.youtube.com