I saw an IRIS-525-X-Ring 120 link chain (Spanish) on a special introduction price, in one of the local shops, a few days ago. I gave it a skip after a search on Google. My current preference is for the DID-525-VX 120ZB, when I can get it. The other chain brand that I would love to try, is the EK chain 525 SRX2 (525 MVXZ) or the EK chain 525 ZVX3. The screw type master link, looks easy to use. So far I have not seen the EK brand on sale over here.
I have tried the all steel sprockets, with and without the rubber damper. Certain sump guards seam to amplify the chain noise, but there are ways of getting around that. Otherwise it is as you say, pot luck.
There are videos on testing of the cush rubbers. I have shimmed mine with inner tube before, with good results, while new cush rubbers were being sourced.