I'm all for migrating to git, but at least one aspect of the OpenBSD workflow would take some serious thought to migrate: CVS supports having one giant repository containing everything (at least, as well as it supports anything else), even including project source code, whereas git really wants smaller per-project repositories that share common history with the corresponding upstreams. In light of that, migrating to git would require some non-trivial workflow changes, making it understandable that it hasn't happened in a hurry.