There was one for sale on Craigslist a few weeks ago in California that stated it was 250-300lbs if I recall correctly. I don't think it had 9" jaws though (no pics were posted).
I know a guy that was told about a vise in England with 12" jaws, but once again, there weren't any pictures to verify it, so your 9" has the largest jaws of any that I have seen (keep in mind I'm fairly new to this, so I haven't seen a lot compared to others).