Deluge
I was seeding about 1200 torrents.
Deluged 1.2.3 crashed with a segfault.
When I restarted it, it only found about 700 torrents.
I had to manually re-add the other 500 torrents, which was terribly painful for me because I rename the parent directory of each torrent to follow standardized naming scheme.
The date on the torrent.state file was the same minute as when the segfault occurred, so I am presuming it died in the middle of writing it out, but there didn't seem to be a back-up copy of the original.
So, I would like to request a more recoverable state saving process, crashing should never cause deluge to totally lose all record of a torrent. I can deal with it forgetting about the last few blocks that were received, but not to completely lose all track of the torrent.