Amethyst Damage Detector

I've had the idea for a Damage Detector for a while, but the addition of amethyst enables this idea.
The detector would be crafted with an Amethyst Block and 4 redstone dust, similar to the Target Block.

Unlike the Target Block, though, the Damage Detector would activate (giving a redstone pulse of power 15) on being hit by a player, allowing players to use it as a more convenient button, seeing as how buttons have a rather small hitbox.

The actual damage detecting comes in when a comparator detects its state: the comparator outputs the 'damage' that the block takes, with the power being the amount of damage in half-hearts.

The main reason for this is that it allows the Damage Detector to be more versatile, and it is consistent with the behavior of other blocks.

The Damage Detector would also act like the Target Block in terms of redstone directing, which would be useful as target blocks are (A). Expensive, taking 9 wheat per-block, and (B). Flammable.

This also gives players interested in redstone a real reason to visit the amethyst geodes, as at the moment they are only a curiosity.