I am not even sure why key down/key up is still being debated. It is in the API there are several popular addons that have this ability.

As far as steps in ISBoxer this is a one press one action function.

Anyone who uses Macaroon, the old Trinity, and a slew of other addons that allow you to perform actions on key up and key down are cheaters than? If so I bet you 99.9% of those people are NOT multiboxers.

I know many serious Arena players who use these mods to trigger actions on keydown to speed up reaction time.