I don't know anything about the Shimano 12sp, but sram has been an absolute pain in the arse to tune right. It's possible that it's another sram thing though, their mid range 11sp was definitely not as robust as the Shimano equivalent.
But as much as I love the 11sp Shimano gear, if I was in your position I'd probably just hold onto the 12sp stuff. Chains shouldn't be much more expensive and if you change them fairly regularly you shouldn't be changing cassettes all that often. Add the microspline challenge and you won't get ahead going back to 11sp
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