When doing a break off move you must consider your ennemy movement capacity .

So if your opponent's TUG is in ORB it's speed is 1 MU maximum, the speed taken into account for a break off ...

Seems to make sense that it should ... also terrain?

Yes, the QRS does mention max speed in terrrain.  As you say any troops in Orb, their max speed is 1MU in any terrain.

Richard

That was also my reading but so it is written

Exactly so...
S