Thanks to everyone who responded. After discussing this with various people off-list, the project team will merge together the functionality of the existing bzip2 application, with what is available via pbzip2. When this work is complete, they will come back to PSARC, with a revised proposal and specification.
Until that time, I've adjusted the case to "waiting need spec", (rather than withdrawing it), so that the mail archive preserves the case history.
