There have been reports in the gigabyte range, where several gigabytes were reported lost.
I was under the impression that your download is reported whether or not you receive all the pieces in good condition.
Also, people have reported having finished torrents from scratch with a final tracked download significantly lower than the file size, sometimes less than half.
Xiong: Fair enough, I guess. I'm more under the impression that we don't really try to reproduce the problem, though, or at least pay attention to whether or not we have the same problem. I know I haven't been making an effort.