A quick comment as I begin my review...
The notion of limiting the countdown timer to never exceed 6 might need some additional thought / testing. The Rebels will only have 4 opportunities to add time to the clock. If they happen to roll well on their first node kill and bring the clock back up to six, I'd hate to leave open the possibility that the Rebels would be forced to call off an attack on a 2nd node in the same turn to avoid the loss of added time.
I'm already anticipating that the nodes will be positioned at the ends of the node setup area - Imperials will place theirs furthest from the entry area, Rebel nodes will be placed closest. Coordinating attacks on the nodes to ensure you don't lose an opportunity to add time on the clock may not be very cool, especially if having to turn around to accomplish the attack may then in turn burn additional time to get back on track towards the trench.
Some thought ought to be given to raising the upper limit (or eliminating the limit) on the clock. Let us see how the playtesting goes...
Edited by Biff