Warning: Showtime added new data to The Sims 3 folder, and doing a full "factory reset" will cause you to lose data relating to your in-game achievements and SimPort progress.
No, it will
not.
Carl and I were literally just discussing this. He mentioned that once, while doing a factory restore, he forgot to put these files back where they belonged and mentioned that it recreated itself. So I experimented with it myself to see what impact this had on my achievements. I removed both of these files, started my game and went into a save to check my achievements.
They were all there.The ChallengeData.package file
only stores your completed achievement data on your computer in case you're not online. This is the file the game uses to update your achievements you complete when you're not logged in.
I have not yet tested the SimPort file, as I have not used SimPort yet...but you better believe that I will at some point soon.
So for now, you have nothing at all to fear with your achievements.
Edit: If you have not tested something yourself, and do not know it to be
100% fact,
do not present it as such. In cases like that, we use phrases like "I hear" or "I think" so that people are not needlessly frightened over something that turns out to be nothing. If you do this, people can test things to find out for sure if what you hear or think is true. In this case, you turned out to be at least 50% wrong.