The great thing about non-destructive photo editors such as Apple Aperture and Adobe Lightroom is that they do not make changes to the original photos.

You are concerned about the corruption of the Aperture Library. The library contains references to the original photos which it calls masters. It also contains other data such as additional files derived from masters(versions), projects, albums, folders, vaults, etc. But still you have to remember that your original files should be untouched.

You can read in forum after forum examples of people having XXXGB of data comprised of XXX,XXX number of photos and their library corrupted. Giving more examples of that here isn't going to do much but provide one users experience which is not likely representative of the entire user base at all. Apple has before noted that a single Library should be able to support 1,000,000 images. I wouldn't recommend that, but 1TB of data and 100,000 images should be just fine. You have somewhere around 25% of that, and wouldn't typically be a concern to me.

I would recommend just building a single library unless you have some significant distinction that would make sense to split the data up. Examples would be a "work" library and a "personal" library or similar. Other than that, don't worry about 1 or 2 anecdotal examples of issues, and just build a single library with your photos, because remember - your master/original files will not be harmed even if your library is corrupted.

One way to help yourself cope with any library corruption, would be to keep monthly(or so) backups of your library. Then if it does get corrupted, simply roll back and you only lose library changes back to the last backup(but not any originals). This is what I do and it works very well.