It's worth bearing in mind, that the more that people do this sort of thing, the faster it is likely to bring acf down, since eventually it'll reach some sort of bandwidth limit, and I doubt sam will rush to deal with it.
If there are certain things which you must have, then all well and good, but I wouldn't just download every post you ever made, "just in case", since out of context of the threads they are in, they are likely to look a bit strange anyway.