Advantages of UDF:
[I] * UDF is an open standard.
* The design and evolution of UDF keeps compatibility in mind.
* UDF natively supports many modern file systems features:
o Large partition size (maximum 2TB with 512B block size, or 8TB with 2KB block size)
o 64-bit file size
o Extended attributes (e.g., named streams, or forks) without size limitation
o Long file names (maximum 254 bytes, any character can appear in the name)
o Unicode encoding of file names
o Sparse file
o Hard links
o Symbolic links
o Metadata checksum
o Metadata redundancy (optional in UDF 2.50 or later in metadata partition)
o Defect management (for media that does not manage defect internally, such as CD-RW, DVD-RW, and DVD+RW)
* UDF defines how different platforms interact with each other. For example, it defines how to store Mac Finder Info and Resource Fork, NTFS ACL, UNIX ACL, OS/2 EA, etc. It also requires platforms to preserve the information that they don’t understand.
* UDF is a truly universal file system. It can be used on all kinds of optical media, including read only (CD-ROM, DVD-ROM, BD-ROM (Blu-ray Disc Read-Only)), write once (CD-R, DVD-R, DVD+R, BD-R), rewritable (CD-RW, DVD-RW, DVD+RW, DVD-RAM, CD-MRW, DVD+MRW, BD-RE), and of course block device (hard drives). Even write-once media appears as a big overwritable floppy under UDF. [/I]
Taken from here: http://homepage.mac.com/wenguangwang/myhome/udf.html
For your purposes, writing data to write-once BD-R disks, 9660 + UDF 1.02 may not have many advantages over Joliet other than file lengths/characters, and directory depth. I believe UDF is better for multi-session, but I don’t recommend multi-session burns on dvds, much less BD-R.