Yay! That's a big deal!
Thom, I suggest you consider making "warp state" a speedometer that gives the true speed combining Helm setting and Engineering power allocation. It would also be useful to the players (and more Trek like) if that speedometer showed up on the Helm console. The current bar on the Helm console only shows what the Helmsperson has selected, it doesn't tell the Helmsperson how fast the ship is moving.
The setting selected by Helm doesn't tell my script how much time it will take the players to get from point A to point B. Knowing that time is important to story exposition. Also, if my script has an action triggered by Warp 4 the players can cheat by having Helm select Warp 4 while Engineering cuts power to the Warp drive.
"Damn the torpedoes! Four bells, Captain Drayton!"
(Likely actual words of Admiral David Farragut, USN, at the battle of Mobile Bay. Four bells was the signal for the engine room to make full steam ahead).