Where we stand now is on firm footing anyway. So far, only one starship has used the drive successfully and survived to tell the tale. Except they aren't telling: they quite deliberately do this Lone Ranger act where those saved by the drive never get to thank or even see their saviors. And it all happens in wartime, under great secrecy, and nothing that gets accomplished could credibly be connected to a superdrive existing. If the accomplishments even get acknowledged, that is.
In-universe, the spore drive does not exist as of 2257. Nor do Mirror Universes. A dozen other things might "not exist" at the time, too. Too bad cloaks of invisibility are not among those, but instead are headline news, at least on Starfleet Weekly.
Timo Saloniemi