Also did another review of the numbers to check on MP efficiency of the Cures after the suggested scaling changes, in case that might have a notable impact on the viability.
This change does have an impact on the relative order of MP efficiency. With the current model, Cure 5 is about 19% more MP efficient than Cure 4, and about 27% more efficient than Cure 3. With the suggested revision, Cure 4 is about 8%-9% more efficient than Cure 5, and Cure 3 about identical to Cure 4.
Even so, the change raised Cure 5's efficiency about 2.4%, so it's not really a 'loss'; it's just that the lower tier cures gained a lot more. Given the low-hate nature of Cure 5, I don't think being slightly less MP efficient relative to the lower tier cures is that great a burden to worry about.