I tried searching for some permutations of "works with new releases", but wasn't able to find a thread on this topic, so...
Are there ways to guess which features of a fortress from an old release will remain unchanged if the save is moved up to the new version? Similarly, how about features of a new version which will not affect old saves? I have almost always abandoned my previous fort to create a new one with every save since they're mostly disposable, but recently I got a real beauty of an embark and I want to keep it around.
There are a few ways I can guess at these things. Changes that modify raw files tend to not work unless the player goes in and alters them in the save's raws, of course, but I remember reading that occasionally a change to the raws might create major bugs if the player goes and fixes them in a moved save. Added creatures and creature parts are something of a gray area for my knowledge here.
I also know that many non-raws game mechanics changes are brought to the old save when it's moved to the new release's folder, but not all of them. This is the primary reason for this post. I'm guessing my .22 fort, which did not yet have a hospital, will probably have all the functions of a .25 fort's healthcare system when I move it up. However, many things can affect dwarves and their jobs, which are saved in a different format from raw files.
I don't know if these changes might build up and create bugs later on; one of my forts between 31.14 and 31.16 may have had some issues in this regard, and it simply didn't gain many of the functionalities of the newer version. I haven't tried moving any forts forward across versions since. Are compatibility problems between releases generally not noticeable, or does it become unimportant with some copying of the raws? Any observations about this would be good to know.
If nothing else, is it possible to generate identical worlds in .22 and .25, or do new releases always mess with the generator somehow? Other threads I read weren't clear about that.