The described change is that they're cutting the cost in half, slightly reducing resources restored, but giving back a large chunk when the effect ends.

My hopes is that the "chunk" restored will work similar to Rally; where if you were to reactivate the ability early you'll receive a % of that chunk based upon the time left of the ability.

For example: Siphoning lasts 20 seconds

When the effect ends you'll receive 4000 stamina/magicka; however if you reactivate the ability after 15 seconds, you'll receive 3000 stamina/magicka instead.