Take it (2 DP) when you want to play the grinding, punishing version of AdMech: soften the enemy before the first turn, force uncomfortable early decisions, and win on accumulated chip damage and Battle-shock rather than on one big alpha strike.
It is at its best against armies that want to stay home: castled gunlines, reserve-heavy lists that leave units in their deployment zone, and anything that dislikes Battle-shock tests. It is at its worst against fast armies that vacate their deployment zone by turn two, because the Fallout stage simply stops finding targets. Radial Suffusion partly answers that, which is why it is the most-taken enhancement here.
At 2 DP it leaves 1 DP for a support, and it needs one: nothing in the detachment protects your characters.
Sample gameplan: deploy Rangers or Vanguard as your Battleline spine, with Sicarians or Hastarii within the 6\" extension range. Resolve the turn-one bombardment, then push forward under Conqueror so the +1 Armour Penetration clause stays live near Battleline. Use Pre-calibrated Purge Solution while the enemy is still at home, spend Bulwark Imperative or Baleful Halo when your key brick is targeted, and cash Extinction Order in the Command phase against a crowded objective. Take Radial Suffusion so the Fallout keeps landing as the enemy edges out.