I decided that this question might come up eventually and be useful to new(ish?) players.
What are the "speed classes" that exist in this mod and which ships belong where?
Fun fact, the Geisha's unique engine that gives it an extra six or seven cruise speed is a swapable Light Transport Engine that can be mounted on any other small transport, but the only way to get it is to buy a Geisha and take it off the ship.
The Bretonian Liner has Cruiser speeds. The Renzu Liner has Battlecruiser speeds.
The Passenger, Luxury, Gallic and Pilgrim liners have "normal" Liner speeds.