floomby: Why don't you tweak your settings so Impaler doesn't fire at moving radar dots by default? It will miss less then.

I didn't know you can tell impalers to only fire at static radar dots.

Turning off fire-at-radar only stops you firing at radar dots that could potentially move (units and unidentified dots), not identified buildings.

To switch the default, change the setting at Menu->Settings->Unit Behaviour->Default States->Rover Assembly->Impaler->Fire at Radar.

The command description doesn't accurately describe what it does, if what dyth68 is saying is true. It only says that it will stop firing at radar dots.