Maximum length of total pathname is set by MAXNAMLEN. It is usually set to 255 bytes long. If you have a very long pathname, then you may cause taper to segfault.
If a file grows while taper is trying to back it up, only the beginning part of the file is backed up (specifically, the number of bytes the file was when taper started to back up this file) and the rest is lost. This is because of inadequate mandatory file locking. I know that this is being worked in the kernel and hopefully, when the kernel code pertaining to this is stable, I can implement it in taper.