Of course, git itself doesn't really have any rename support. It adds it in the UI with a similarity metric.
But it would be nice when importing git repositories if hg-git would make some attempt to use similarity metrics to notice copies and renames and use Mercurial's built-in rename support.
I find Mercurial's diffing and searching tools to be far superior to git's and often find myself importing git repositories just so I can use Mercurial to search through them for stuff or do diffs between revisions. But Mercurial not tracking across renames has been a bit of a problem sometimes when using hg-git this way.