Changing Ubuntu Cloud Repo On Instance

Ubuntu instance images seem to utilize "nova.clouds.archive.ubuntu.com" as their default repository. It seems that either this server does not efficiently route to an alternate mirror, or it itself is a mirror. This results in quite abysmal download speeds that I have seen. Would there be any downside to picking any other Ubuntu mirror, that is definitively more geographically close to me, but not explicitly labeled a Nova/Cloud mirror? i.e. would there be issues encountered, or features lost, by not using Ubuntu's designated Nova/Cloud repo?