Well, that didn't take long:
According to the skirmish tests I ran and the information in this thread, the firebird models currently stand as follows:
Problems with soldiers phasing inside the back wall:
+bomber_city
+cemetery
+city_disco
+community_centre
+construction (entire firebird craftdrop tile impassable)
+desert harvester_crash
+druglord
+eaglenest
+gasstation
+italy
+japan (japan_big has map name +japan small and freezes UFOAI when loading a skirmish)
+mart
+oriental
+military_convoy
scout_crash
+shelter
+spedition
+stadium
+transport
+village
Fixed:
+laboratory
+forest
+bridge (should be)
I did not test the maps that did not have a dropship specified. In the
Firebird Model Problems thread I asked about a couple of things related to the model. There are two possible fixes: The one used in +forest and the other used in the +industrial and +city Firebirds
Now that I've seen both version, I would prefer the one that is used in +forest where the soldiers are close to the back wall and it would be great if it was the same in all maps. If that fix could be coupled with a new firebird model where the doors were a bit wider from behind the engine intake to allow three soldiers to walk abreast (see screenshot from +hills map to see what I mean), that would be super.