Good points.
Borg transwarp might be better or more reliable. The Borg have likely assimilated numerous drive technologies, like slipstream in 2374, and stuck to transwarp anyway.
The other parties may not get access to the tech due to Starfleet counter-espionage. In the novels, Starfleet has been able to keep QSD out of the Typhon Pact members’ hands for years.
Borg transwarp might be better or more reliable. The Borg have likely assimilated numerous drive technologies, like slipstream in 2374, and stuck to transwarp anyway.
The other parties may not get access to the tech due to Starfleet counter-espionage. In the novels, Starfleet has been able to keep QSD out of the Typhon Pact members’ hands for years.