Official GW 40K Errata and FAQ (7th edition link on page 7)

[jaqenhgar]

Seems like they nerfed the DA one because it was too powerful in combination with landraiders if the pfg is inside one. With orks the BW's are AV14 on the front armour only, and usully open-topped so are much easier to destroy, plus I think the KFF is only a 5+ save on vehicles now?

So consistency wise it's unfair, but probably a game balance issue.