Moving that setting to the main config file wasn't intended to be a fix - it was simply an observation that it is simpler to put global settings in the main config file.
The XferLOG.bad file can be accessed from the client's status page via the web interface, or from the command line. If HOST is the one that failed, and the data store is in /data/BackupPC, then the XferLOG.bad file can be found in /data/BackupPC/pc/HOST/XferLOG.bad.z. You can uncompress it with:
/usr/local/BackupPC/bin/BackupPC_zcat /data/BackupPC/pc/HOST/XferLOG.bad.z
Please also tell us your settings for $Conf{XferMethod}, $Conf{RsyncClientPath}, $Conf{RsyncSshArgs}, $Conf{RsyncShareName}, $Conf{RsyncArgs}, $Conf{RsyncFullArgsExtra}.
Craig