When using Holoecho L2: Let's say I spend two orders to suicide my holoechoes against two enemy mines. Does my trooper automatically drop out of holoprojector L2 state at the conclusion of the second order? What if I were combining the effects of both Holoprojector L1 and L2?
Yes, because you no longer have coherency with another Holoecho, which is a cancellation clause of the Holoecho state.
Note, this has no effect on you combining Holo 1 and 2. You still look like whatever you're pretending to look like.
No, because you're separately in a Holo 1 'State' and the Holo Echo state in combination. Only half the combination's cancellation criteria have been met. I'm fairly sure that this has been hashed out on the old forums. Edit: apparently it hasn't been / I can't find it.
You'd still be holo1, but that alone doesn't really buy you much. By the time your opponent has stripped off a pair of holoechoes it's pretty clear what's going on, and the number of possible units that the model could be is quite limited. Other than hiding what loadout a model has, holo1 doesn't really provide any benefits.
You can't break coherency with dead (as in removed from the table or left there as a body) troopers or markers, really... I am aware, however, that there are no rules covering this issue and it's my personal interpretation. Simply put, eliminating both the echoes while the trooper remains on the table means it still is in Holo2 state, so it is still a marker state and able to perform a Surprise shot. We should remember, however, that you can shoot a holoprojector marker without needing to discover it, so in the reactive turn it has little effect by itself. Certainly, I wouldn't know if that Ghulam sniper hiding there after blowing his two echoes is an Ayyar or a Bashi Bazouk until the orders phase of its owner... and once it reaches it, I wouldn't know still the loadout. Those are the only advantages for the state not being canceled.
You appear to be remembering the Coherency rules back-to-front, Coherency has to be actively checked rather than being a passive state. :-( You make a Coherency Check, checking ZoC from your Reference Trooper. The Coherency Check will automatically fail if the other item has been removed from the table, because they're not in ZoC of the Reference Trooper. If a Coherency Check is failed, then Coherency has explicitly been broken: 'When a Coherency Check is failed, if a trooper is out of the Reference Trooper's ZoC, then Coherency is broken and its consequences are applied immediately, as stated by the rule, Special Skill, piece of Equipment... the player is applying.' My emphasis. There is no ambiguity for a trooper with no decoy Holoechos left: the Coherency Check has failed > Coherency has broken > the Cancellation bullet has been fulfilled. No additional Holoechos = no Holoecho state.
Sigh, got confused with english translation while skimming over it (that "for example" as translation for "so" made me skip some lines). Yeah, reading in detail, you lose 2 echoes, you lose ALL holoecho marker status. However, RAW you replace the "marker" for the Figure, so if you combine Holo1 + Holo2, you should still have Holo1 after losing Holo2.