Maybe I am stupid or something but I feel Monterey runs better on the MB12 2017 then Big Sur. If I remember correctly I got way more of those colored balls during several tasks then I do with Monterey. Only battery life has declined a bit imo and it takes just a bit longer to wake from standby.
Somethings else...
I just got the MBP 14 M1 Pro because of that nice almost bezel less Mini Led display. I couldn't resist as a MB12 lover who waits for years now for a successor. And of course performance is like night and day. And display quality is amazing.
But what I really am shocked is just how well the MB12 2017 i7 8GB 512GB still runs with Monterey. And how good that display is honestly. Of course the MBP14 has a way better display, sharper, more contrast, better blacks. But really, for a LCD display from 2017 quality is amazing.
I will definitely keep the MB12 because I wouldn't get that much money for it anymore and I just love it. I just wonder now if I could really wait one more year for a MB Air 2 which seems to have similar display but smaller. It could go to MB12 size if Apple shrinks the bezels and keep the display size. I am torn. My MB12 just runs amazing considering everything. Even keyboard is in perfect condition. Only battery must be changed in the near future. Would cost 200$ ...