Fridge Logic: So, if the starslip drive works by swapping the ship with one in an alternate universe where it's already where you want to be - doesn't that mean that, from the perspective of every single reality, the ship just stays there, immobile but for sublight, forever?
Also, how did the parallel version of the ship get there in the first place?
According to Deep Time, Starslip is "a cheat"; presumably they used a more legitimate means.
It doesn't need to stay immobile, if the ship in another universe starslips into its location and picks up from there. Considering the massive use of the starslip drive, and the infinite number of universes in play, it seems not only possible, but quite likely.