Is there a reason not to use --mirror when pushing?

[jdom]

I'm looking at a VSTS task that will help me mirror a github repo to a repo in VSO, including pull requests (which are under refs/pull/*. Nevertheless I did not find any in the marketplace that works out of the box, but was wondering whether you would be willing to take this update (either by explicitly pushing those refs too, or even possibly just using --mirror instead of pushing --all and --tags separately).