What are the details of the Thor's new High-Impact Payload mode?

In Heart of the Swarm, the Thor's Strike Cannon were removed, replaced by an ability called High-Impact Payload, which is supposed to be good against air units. But what are the details; I cannot find the numbers or good discussion of tactical advice for it.

Specifically:

• Is High-Impact Payload better against all air units?
• Can a Thor still attack ground units in this mode?
• If you are under air attack, is it worth it to shift modes, or will the conversion time reduce any benefit of the High-Impact Payload? (Like Siege Tanks caught unsieged)

Solution 1:

The high impact payload swaps out the Thor's anti-air capability from being effective against swarms of light units (explosive/normal) to single targeting armored units (high impact).

In explosive payload (default, classic mode), the Thor does 4 missiles of 6 damage (+6 vs light), with a 3 second cooldown. Effective against units like mutalisks. Note in this mode, against unarmored the missiles do the same amount of damage per shot, but slower. Against armored targets, each missile is reduced by the armor amount, taking 4x the penalty of the high impact payload.

In high impact payload mode the Thor does 24 damage to a single target, with a 2 second cooldown. Effective against units like void rays.

source: gameplay and liquidpedia