I discourage ReiserFS for panic under heavy load:
REISERFS: panic (device Null superblock): vs-7042: entry_points_to_object: entry
must be visible
ReiserFS works quite realiably until it is stressed with many concurrent accesses. You can read about it here.
Just now I have Maildir (around 200GB) on ReiserFS. During last two days FS crashed two times and I'm looking for a way to resolve this problem (seems like using kernel 22.214.171.124 helps). Later I will try to migrate to JFS or XFS.
ReiserFS seems unmaintained and for sure have existing bugs. Its speed does not compensate for its problems. It is not realiable solution.