The four different Standards would have four different Object Defaults styles, which would refer to four different Parts List styles, but everything else would be identical and refer to the exact same styles. That is, the four Object Defaults refer to the same styles for every other category, so if you modify your text styles, no problem-- all of them use the same text styles, so no synching necessary. The only difficulty I can see is if you frequently add new styles or change names, then you have to make the change to each of the four Object Defaults styles separately, but that still doesn't seem like very much work unless it's very frequent.
Am I misunderstanding something?
Sam