Mm, what I was thinking for the drain rate was that it only effected the 'passive' recovery rate of someone's Aura. Something along the lines of...

Randumb gets +5 Aura every second.

Arara takes +2 Aura by leeching off him.

Randumb thus actually only gains +3 Aura per second, but his existing pool of Aura is not effected.

Unless, of course, when using Aura, people can't passively recover it.