I'm a bit bemused by all of the new wording from the new rulebook.
The new rulebook says a flyer can move "flat out" during the shooting phase in place of shooting - essentially a run move like the infantry get.
This maneuvore is specifically labelled "flat out".
Disembarking from a vehicle cannot be done through the shooting phase.
Yet on pg.56 of the Imperial Guard codex is states under the Grav Chute Insertion rule: If it moves flat out the squad can disembark following particular rules.
I've summarised here but it does state the words "if the valkyrie or vendetta moves flat out" and is then following by an explanation of the unit being allowed to disembark.
If looked at the errata and no help there. Anyone care to have a go?
To me, this says I can disembark during the shooting phase.