Then too there was the Varduuar "underspace" which looked like they stumbled into Babylon 5's travel method. Quantum slipstream seems very like SW and Stargate hyperspace--all isolated from the rest of the 'verse. Transwarp, like regular warp, still allows for some interaction with a ship that passes by systems and can scan them in transit (unlike JJ's movie, which has a strange quantum distortion/warp hybrid...
Perhaps Transwarp is really a very shallow hyperspace kept at bay with warp fields themselves.
The Voth city ship and AGT ENT-D seemed to master the effect, as did Paris shuttle.
The evolution-defect was a result of a virus we will say, that lived in hyperspace, where Kirk hung out in Tholian webland...