yo, congrats on the R6 II upgrade! literally such a beast of a camera. i feel u on the lens situation tho, those L-series beauties are hard to let go of. tbh i tried to save some cash at first cuz the official canon ones feel like a total ripoff for what they are. i started with the Viltrox EF-EOS R Mount Adapter and it was okay for a bit. but honestly? i was pretty disappointed. i noticed that 'wobble' u mentioned with my Canon EF 70-200mm f/2.8L IS III USM, and it felt super sketchy when i was out in the field. plus, the AF felt just a tiny bit sluggish during burst shooting for sports compared to native. i dont think the weather sealing is actually legit on the cheaper ones either, which is scary if ur shooting in the damp conditions u mentioned. so i eventually gave in and got the Canon Mount Adapter EF-EOS R. basically it’s perfect. no play at all, feels like one solid piece with the body. i also looked at the Canon Control Ring Mount Adapter EF-EOS R, but imo it’s not worth the extra $100 unless u REALLY love having that extra dial. i tried the Commlite CM-EF-EOS R Mount Adapter too and it was just as loose as the viltrox... not as good as expected at all. seriously, dont risk ur L glass on a $50 tube. i regret trying to be cheap lol. gl! peace ✌️

sooo i tried a cheap knockoff at first but the 70-200mm wobble was highkey scary... basically felt super sketchy. if you need reliability, i'd suggest the Canon Drop-In Filter Mount Adapter EF-EOS R with Variable ND Filter. it has better gaskets for weather sealing and the communication pins are more precise. maybe ask a pro shop to test the fit first? lesson learned: dont risk your L-series glass on cheap metal. gl!

tbh looking at the current market research right now, it's a bit of a minefield because different brands use totally different tolerances for their "pro" vs "budget" lines. I've been super cautious about this myself because the cost of a mount failure is just SO high compared to the price of the adapter... basically, you're paying for the quality of the alloy and the precision of the weather-sealing gaskets which varies wildly between manufacturers. Before you pull the trigger on anything, I’ve got a couple of questions to help narrow down what'll actually be reliable for your specific workflow: 1. Are you planning to leave the adapter permanently attached to one specific lens, or will you be swapping it between your EF glass frequently while out in those dusty/damp conditions?
2. With the 70-200mm, are you usually supporting the setup by the lens foot, or is the mount taking the full weight of the glass most of the time? That "wobble" usually stems from the locking pin mechanism wearing down on the cheaper builds, so anyway... definitely worth thinking about how much stress that joint is actually going to see.

Same boat, watching this

Adding my two cents here... making the jump to mirrorless is huge but keeping those L-series lenses is definitely the right move. If you wanna save some cash without sacrificing performance, I'd check out the Viltrox EF-R2 Control Ring Mount Adapter. It basically replicates the more expensive control ring versions but for way less money. The build is solid metal, and the AF tracking for things like wildlife is actually spot on cuz the electronic signal pass-through is basically 1:1. Another solid budget pick is the Meike MK-EFTR-C Drop-in Filter Mount Adapter. It's a great value alternative to the official drop-in version. Honestly tho, if you're worried about that "wobble" with a heavy lens like the Canon EF 70-200mm f/2.8L IS III USM, the Viltrox usually feels a bit tighter in my experience. Third-party adapters sometimes have slightly looser tolerances which can affect the weather sealing integrity. If youre gonna be out in the mud and rain constantly, the official ones are safer for the gaskets, but for everyday professional use? The Viltrox is a total steal. gl!