DarkCookie has tried making saves that are close together in updates compatible but its still an early process and not 100% full proof, so from about v0.19+
He also re-did some of the early game content as well, the truth of the matter is saves wont be "safe" until he officially gets the compatibility in order, or just get use to using the provided saves from each new update.
Also should go without saying but you are better off not using any mods, most of the modders for SS dont really do a good job and end up bugging out your save so its not worth it imo.
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