Since getting my 622 two years ago, I’ve stopped looking for the next best thing. I love this horn and I love the sound the Yeo mouthpiece gets on it, but the flat rim is becoming problematic and painful and my beloved Chinook doesn’t work well with the horn. Schilke 59 and 60 seem to work well for sound but struggle with intonation. Anyone with a 622 or 822 recommend any mpcs that work with this horn?

If you like the rim on a Chinook you could have someone thread your Chinook rim on the Yeo. Or get an Elliott rim and thread the Yeo for it. Although honestly, you might want to consider getting something stock since that could actually be returnable if you end up not liking it. I played a 622 for a recording session a few months back. I ended up going for something with a relatively similar rim (my LB114, but in lexan) and found that a shallower cup but a more open backbore was really well balanced. I think I ended up using an LB114/J/J9.

You’ll likely need something Yeo-esque. He designed that horn (I play an 822G) to play well and center with a large mp. Maybe try a GW Kariff. Same relative size as a Yeo, but stainless and different rim.

The Bach Artisan 1G is a very similar size to the Yeo and has a rounder rim. It's very different from a standard 1G.

If you can get your hands on one, a Greg Black 1-1/8 G with the .312 throat and #2 backbore will also be similar dimensions to the Yeo with a rounder rim.

Doug Elliott's rims are also fairly flat, but I find them very comfortable. 113 or 114 rim, probably L cup but maybe M. The XB series is worth a try in addition to the more common LB.

Finally, a standard Stork 1 might be a good fit.