I guess talking about how evil life-tap is for Clerics isn't so OT because it was also raged about in OP
From the Mage point of view though, I guess that as long as you let the Cleric know and not abuse the skill, that life-tap isn't that bad. Even before they buffed-up Heal's potential by making it enpowerable, the off-set between the small amount of SP the Cleric uses for the large amount of HP it restores + the potential benefit to party-dynamics and working for a party that works well together is a good thing.
Even consider the mechanics of stone usage. Clerics and Fighters have a much larger capacity for both kinds of stones than Archers and Mages. To offset the Mage's lower SP stone count, he/she can life-tap with the Cleric's consent. The Cleric thus sacrifices SP stones of their own/ time shrooming, but this is offset by the low amount of HP stones the Cleric uses so it balances out anyway.
Then again, most if not all complaints about life-tap comes about Mages who use it unexpectedly/ at stupid times, so I guess the point is moot >__>