My goal for each of these games is to offer some rules variations you could (but don’t need to) use with the other games if you want. So no, I haven’t revised any of the earlier 2400 games to use the Legends armor rules, but yes, you are absolutely welcome to replace the other games’ heavy armor with how heavy armor works in Legends. 

I am not sure what you mean by an armor saving throw, but my general philosophy is to not add extra rolls when playing 2400, if I can help it. I’d personally rather just say that some armor obviates the need for a roll at all, or makes if so the risks of a roll are less (like “get hurt” instead of “get killed”). The rule about breaking armor is designed mostly as a safety tool for players who worry about losing characters, but it’s also inspired by real-world ballistic armor (and bike helmets!), which does indeed need to be replaced after absorbing a potentially lethal blow. 

On a side point, the "armor saving throw" implies an instance of: you're being attacked and rolling to see whether the attack can make it past your armor to hit, damage enough to hurt you, etc. While in 2400 games, the more general OSR-esque skill system doesn't really frame battles that way. It's more d6 resolving the  outcome of the overall situation. I guess you could slot in an armor class there ("If skill roll is over 3, armor is only dented, not yet broken"), but then it just complicates the outcome of the skill roll. Did you get a "Lesser consequence" still from roll, but now it can't be a physical wound? It's adding another layer.
Also, using armor as an added protection from bad outcomes (at the cost of breaking it) makes a lot of sense. It might even be more helpful than just for battle, since you could conceivably use it to deflect/soften any bad roll. It's logical to me that you would trade armor breaking for your own skin NOT breaking. Since, that's what it does in real life. It just has that OSR-esque simplicity: cuts right into what something does in a sort-of binary and succinct way.