Should Decoy Markers have 180° LoF like Holoecho markers do? As the rules stand they don't appear to have any mention of facing in the Decoy rules where Holoecho state is quite specific about having them. It seems like you basically get 360° LoF while in decoy state if you make the real trooper one of the markers instead of the model that has an actual LoF.
The rulebook states that if a trooper with Decoy is placed as a model in the table, the decoy markers are considered as models for LoF purposes and may be targeted, so no, Decoy should not have 180º LoF because it's not, rulewise, a marker state. I imagine this is taken into account in its cost.
Decoy for camo tokens:I think 360. Since a camo token has 360 until revealed. Of course it can't actually do anything if technically "sees". Decoy for a non-camo troops: is 180 like the figure it's a decoy off.
Notice how the Holoecho markers have 180 LoF marked on them but the Decoy ones do not. Also Holoecho state has this bullet point which is absent in the decoy state.
Decoy is a weak Holoecho. I don't know of any Holo figures with 360 visor, but if had them then they would have it. But decoy can be used on camo and non-camo troops. My question is, why does it matter if the decoy can "see"? Unless you want to reveal, you are going to do nothing with them.
Like Holoecho when you deploy a model you choose if the actual miniature or the marker is the real trooper so you could make the "real Trooper" one of the markers, since the marker doesn't have a LoF marking on it to indicate the 180 degree Lof in this specific case the you effectively gain 360 degree vision (however for this to be true the "real trooper" has to be one of the markers)
This answer seems pretty clear cut in the Cancellation section of the Decoy State. You will find this line: "If the user was hidden as a Decoy Marker, the player must replace the Marker with the corresponding Model, facing in any direction the player chooses." Earlier in the section it clarifies that if you are not in some other marker state such as Camo or Imp then you are a Decoy and Decoys are models for LoF or interaction purposes but you are still a decoy marker. You see very similar verbiage in Holoecho. So my understand of it is, regardless if you are attacking the model or one of the Decoy tokens, all 3 are Decoys for rules purposes. When the Decoy user is revealed (likely because the opponent guessed correctly) then at that moment you can decide facing of the model much like you do with Camo. Post edit: I honestly thought they worked much like Holoecho but they can't move. But apparently not it would seem.