Well, so long as the Healer is not casting a spell over his own level, isn't encumbering himself with inappropriate armor (okay, one disadvantage over the RM2 Healer -- no leather helmet), can talk and has a hand free, hasn't used more the 25% of his Power Points (and given how many more he'll have than in RM2, this is about the same point where the RM2 Healer would have had to stop) and isn't trying to cast it in a hurry (no real point unless he swallowed a "you're dead next round" wound), the RMSS Healer also doesn't care about the -30. He just has the usual 2% spell failure rate. In other words, the requirements for "automatic" casting in RMSS are pretty much the same as the limits on casting at all in RM2 core and casting outside those limits is easier than with the RM2 ESF rules (in fact, one of the complaints about RMSS was that it "made overcasting too easy").