Passives Sensors enable a handful of inexpensive ships access to target locks on the first turn of combat. The most dramatic effect of this lock access is that high quality attacks in the form of Proton Torpedoes are available to lower initiative (i.e. lower costed) pilots.
The ships that can make use of the Torpedo/Passive Sensor combo are:
B-wings (Rebel), E-wings (Rebel), VCXs (Rebel), Gunboats (Imperial), Punishers (Imperial), Starvipers (Scum), and N1s (Republic).
Of these, E-wings could already perform a similar trick due to their ship ability, although Passive Sensors allow them additional flexibility. The cheapest option for a first round Torpedo shot with these ships is 65 points. VCX aalready have a 4 dice primary, and are quite expensive, so this combo isn't bringing anything new. These two ships can be largely left absent from discussion.
The B-wing and Starviper can bring Passive Sensor powered Torpedoes for 57 and 62 points, respectively. These are 3 attack dice ships that are quite expensive when equipped with Torpedoes, but can be expected to contribute. Overall, they probably perform worse with their limited shot single modded torpedoes than a similarly priced, higher Initiative ship that can get double modded primary attacks (compare to Braylen for B-wings and Guri for Starvipers).
That leaves Gunboats (48 for Nu with Passives and Torps), Punishers (54 for Cutlass with Passives and Torps), and N1s (50 for Bravos with Passives and Torps) as the really interesting ships.
These ships all bring a single modded 4 dice shot on the first turn of combat. This is a quality shot, but it's not a game turning shot, on average. There will be plenty of times it only does one damage, and sometimes variance will hit and it will do nothing even against a low defense ship. It's modestly better than a double modified 3 dice shot at medium range, which isn't especially rare in most lists, so a player must be prepared to leverage the other strengths of the ship in order to get value from one of these ships, or their slightly more expensive named counterparts. The main strength of the Torpedo shot is the defense that it denies at Range 3 and the automatic crit conversion. This is where these ships stand out against double modded 3 dice primary attacks. While a 2 AGI ship with a Focus token could expect to take 2 damage from a pair of range 3 double modded primary attacks, expected damage is around 4, with a high expectation of a crit or two going through. Consequently, engineering long range engagements is going to maximize the advantages of these low Initiative Proton Torpedo carriers.
In squads, these ships are all around 50 points, with some variation based on upgrades. This gives them a couple roles to play. A single ship of this type included in a squad leaves room for two solid main line ships, Vader/Soontir/Gunboat or Jedi/Jedi/N1, for example. A pair of these ships leaves room for an expensive 3rd ship, Defender/Gunboat/Guboat or Anakin/N1/N1, for example.
In both cases outlined above, the cheaper Torpedo carrying ship helps thin down an opposing squad to make it easier for an ace to finish off in the end game. Fortuitously, all of the interesting Passive Sensor Torp carriers don't rely heavily on their action for defense. The gunboat has 7 hp, the N1 has 5 hp with a frequent free evade, the punisher has 9 hp. Conversely, it is very difficult for any of these ships to finish off a game if the ships they're supporting are destroyed early. Aggessive play with these ships is probably safer than timid play. It will be better to gamble and lose these ships early than to let an opposing squad have an uncontested engagement with your ace(s).
That's all I've got for the moment, and it's all based on theory so far. I'm looking forward to getting these guys on the table at the first opportunity to see how much weight a low Initiative ship can carry.