It may have taken me over half a year to finish this game, but my Let's Play has finally been completed.
Though, on a side note I do think the Healer's Drive may be a bit broken since you can stack it's effect. While, I didn't use this strategy in the final battle against Darkloft. This little factoid does mean you can basically spam Chisa's best healing impulse as long as Darkloft hits the party with some kind of group attack that does damage.
I suppose some would counter with the fact that you would have to reach the initial 82 points for "I Believe in Us" on your own, but with the advantage of two Healer's Drives at your disposal that wouldn't be too difficult.
Plus the advantage of two Healer's Drives would mean it would also be easy to gain enough impulse to spam Impulse Shift on a regular basis. A move that also provides HP regeneration. As such you could use the move to boost your overall impulse level if the other three characters are injured by at least 24 points. And you could gain an impressive 60 if your brought them all back to full health.
About the only plus side to this whole debacle that I can see is that the effect of Healer's Drive will only activate if a party member actually gains HP. And that some of the ingredients for this item are rather rare. As such you won't be able to use this tactic until the late game, but if you do make use of it. I imagine your foes will crumble before the sheer power of Chisa's support abilities.