I think that this seems fair. I suppose the analogy here would be that of a convoy moving as fast as its slowest member.
So if a ship is damaged in combat the wekest point would be the least reliable system. So when the EPS conduit ruptures, using the ship example you give, it would be part of the Impulse systems, but could well affect the whole ship.
That said, there is an arguement that a targetted assault on the ships warp drive would be based on the better reliability.
DanG/Darth Gurden
The Voice of Reason and Sith Lord
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