Personally I would choose T build dev. I never had a device which ran a stable build.
The other thread you link had success with the T dev build, one argument I made for that is the presence of the vendor partition update, which may help to rule out difficulties experienced in the past. That post concludes with (typo corrected).
However if you are using stable on another device, I can see the merit in staying with that in case some apps behave slightly differently.
I will support you whichever path you take; but you decide and we will stick with that (unless we learn better 
)
Let’s just review “Android versions”
So if you are considering S build or T build there is no MSM download to do. Both builds require
on the latest Android 12 firmware.
May I return to the mention of Android 12.1 as this may be significant.
If you check on your Device #2, can we get any clues from an image of
Settings > About phone > Android version, which when opened will reveal the OS and firmware on the originally upgraded device.
If you simply see Android 12.1 somewhere then we can be more sure to progress I think, especially with the T build.