^yep, Gene and the gang wrote themselves into a corner when they decided warp 10 was the cap.
I always looked at it like Warp 10 entered the ship into time-space
as opposed to space-time
In space-time (where we live) time is linear and space is not, in time-space it's space that's linear and time is not which means that in time-space you are stuck in the exact moment you hit warp 10 but every point in the universe is accessible.
The episode in question made it clear that the affects of time space (as I call it) causes an evolutionary mess which makes warp 10 completely unappealing. .
All it takes for the writers to brush past the warp 10 problem is do the same as what they did with the transporters. The transporters use a Heisenberg compensator, Starfleet just needs to invent a warp 10 compensator to prevent entry into time-space and to remain in space-time.
Anyway, on another note. I'd be interested in learning if it's possible to activate the Slipstream drive whilst travelling through a Transwarp conduit. That must be an incredible speed.