The thread's been dead a month, I know, but hey, my net's been dead for three, so there.

The Red Mage is a lot weaker, a lot less broken and horribly unbalanced in the DoS version, so you'll generally find he's just not as bad-ass anymore. He will indeed rate below the White Mage in HP growth as his is basically lowest. Heck, even back in the NES version of FFIII his HP growth was excruciatingly slow.