Is it appropriate on U&L to ask questions on the form "what is the current status of something on OS version?"?
Asking what the current status of something is would be too localized, always, because the status changes with time. In fact I closed a btrfs question about it's stability for that very reason. However, asking about the status of a specific version of a thing on a specific os version, would not change based on time (e.g. ext4 was either in linux 2.6.28 or it wasn't ). Please be advised though that asking if something is stable enough to use is probably subjective (unless citations can be provided (e.g. ext4 on 2.6.28 was stable on disk format but perhaps not stable for production use) , and could be closed for that reason.