I actually owned the cv 15III back when I shot the A7II. Loved the lens and its size but didn't like the vignette on it on that smaller sensor.
I'd be very curious to try it again on the r2.
The main reason why I'm reluctant to sell the 16-35 for the cv is filters.
I love my ND filters with wide angle. I have the 77mm set of Haida NDs and they work great with the 16-35 for all things landscape.
Not sure how to replace that.
Cv 15 alone doesn't give me that.
The Loxia 21 is an option if I'm willing to go MF.
I was often on the search for the perfect set for wide angle. I still own too many lenses for wide angle. The FE16-35 is fantastic. But the CV15 is also fantastic and much smaller but i often take both with me because i cant decide. I found myself shooting a lot in mid zoom range but its just because i have that versatility. But if you like your 16-35 for that, the sony version is great too and its a bit smaller and most likely lighter. Really, the setup becomes so hefty with an ef adapter.
Two shots i got today. Went to visit my brother the on other side of switzerland, fribourg to be exact. Knowing that he can see the mountains from his windows i thought i am taking the 70-300L with me: