p.1 #1 · Fringer EF -> Z worth it or just grab an R5?
I have been very dismayed by the Z lenses and mostly adapting Sony glass, particularly the ART lenses. I much prefer the Z profiles in C1, general color, system, haptics, etc etc, so I don't shoot Sony, but I did come into a lot of EF primes, and I loved those in my Canon (pre-Nikon) days. That said, I'm considering adapting these to my Z body or possibly giving the R5 a shot...after all, that body and the Canon sensor has caught up to Nikon so why not.
It would be easier to try the Fringer. One thing that really irked me with the FX glass adapted to the Z body is the ridiculous adapter...obviously the mount is much different so that's no way around it ( physics!), but it seems like a very different balance than the EF to the R bodies...and that adapter appears much smaller/cheaper.
Anyway, I know, first-world problems here! But I am eager to try some new glass, and as I'm getting more and more professional work in studio settings, I really prefer the, dare I say, "softer" lenses of yesteryear. Eg, the 50 1.8S lens is amazing! For people? No...I don't think so at all. It's much too sharp. And bokeh is strange, and a little structured across the whole frame.
p.1 #2 · Fringer EF -> Z worth it or just grab an R5?
I have the Fringer and overall it works quite well. Newer lenses work very well, especially in good light. Some slower lenses in dim light can hunt, but overall it’s rather good.
If you plan on only shooting Canon lenses, though, it’d make more sense to have a Canon body.
p.1 #4 · Fringer EF -> Z worth it or just grab an R5?
I use the Fringer (I have v1 and v2 which are essentially the same.. v2 has weather sealing) with Canon glass that has that particular drawing (the 50/1.2, 85/1.2, 35/1.4 version 1) and using the excellent TS-E 17/24/50/90 lenses on the Z bodies. of all the EF adapters that I use, this is the most solid and reliable, well worth the high cost IMO.