Is that a Reiser reference or am I missing something?

The value of the journal having history (with comments and timestamps) is huge. I think what I'd prefer to see is having a start sequence of replay journal, build in-memory structure, optionally move old journal to backup name and write out minimal/compressed/comment-and-timestamp-stripped journal to new file. Optionally could be based on size delta; e.g. write if it's less than half the size of the old journal. This keeps journals as append only, while still giving access to full history. It does require some external management to avoid file usage growth even faster than a single journal; but it reduces startup time, and allows a management strategy like just deleting backup files older than a given date (once they're in cold backup, if needed).