AF mode turns a Young Ship's main weapon into 6AD of accurate mini-beams. Expect 3 of those to hit for nominal 3 points damage. Adaptive armour takes that down to 1 and self repair takes care of that, although the White Star is now minus 1 crew. And the weapon is not even precise any more, reducing the chances of criticals and allowing ineffective bulkhead hits.
Alternatively, since the Shadow will probably win initiative and force a White Star to move first, it can use its beam at full strength, expect 6 hits of which the White Star expects to dodge 3, leaving it with 3 precise triple damage hits. That's the same number of hits as with the accurate AF system, but each doing a lot more harm.
Basically I can see no reason for using AF mode against White Stars, unless the Shadow managed to lose initiative and can't move anything else first, so all the White Stars end up out of arc.
And the White Stars will want to close in anyway - given the Shadow ship's shield and self-repair, they'll want to hit it as hard as possible. The Shadow's normal beam outranges the White Star's laser even before the downgrade, so there's no point in sitting at long range.