You have the GCD's for recalls. And the 100k+ mana you save can be used for more healing. And less spirit. How much spirit is 200k mana saved in recalls? Those stats can then be used for crit/mastery, which further increase your healing. Far moreso than the GCD used to do the recalls imo. And with all the people in here saying use TC, you can't tell me with a straight face and say there isn't time for spending a GCD here and there for big mana return. This isn't wrath anymore.
As for losing the last tick of HST. if it happens, meh, so what. I lost 10% of my HST at the cost of 200k mana saved. zomg, totally not worth it. And you don't recall HTT. It's cheap. Just recall HST and elementals.