I misremembered, while the Kitsune has an open hatch, your vanguard troops stand to the side and the wall right above the entrance blocks vision surprisingly effectively.
You might be at a slight disadvantage due to enemies seeing your agents' legs, but it's only for close range. All the more reason for calling it OP.
Skymarshall's side doors and the tail blockage are quite nice, though, and the craft itself can provide total long-range cover after the initial phase is over, unlike Kitsune's and other Sky-crafts' legs. Kitsune's pilot compartment is not quite as useful as the side doors, although it enables different tactics.
I really like the Lightning, because there the enemy does have to come quite close to see you, and you can pop in and out like no tomorrow, both to ground level and up top. Not every mission needs two dozen agents.