OK, just FYI: I reverted to the default bundles as described in the wiki: http://wiki.macromates.com/Troubleshooting/RevertToDefaultBundles .. and then just used svn to checkout the most recent JSON bundle.
This works fine, making reformatting easy.
I do think a bundles manager makes sense to build in the near future. But for now, svn is fine. Thanks to all for the help!
-- Owen