Slightly tangentially from the Merchants question, I should say that I always use Merrick's sensor rules to make passive sensors more useful in BR and to enhance the tactical feel I believe the game designer was aiming for but slightly missed in the rules-as-written.
In essence, a passive sensor detecting an active sensor-using ship adds together his passive base range and the active sensor base range to get a final base range. So a P:4 sensor detecting a ship with an A:8 sensor blasting out would do it as if the base range of the passive sensor was P:12.
This makes the 'command decision' of when to go active much more tricky and crucial.