The Remaining Healers

[Talraen]

At least early on in Final Fantasy I red mages had better armor than white mages. Worse HP, though, though from the bases it's just three less.

I'll have to do more in-depth research later, but the scales definitely aren't as tipped in the white mage's favor as you seem to be making them.

By all means, please do research! I highly recommend my own guide site, http://guides.gamercorner.net/ff/. It has all the information you could ever want on a game that I've been obsessed with for years.

With that said, I can tell you right now what the conclusion is. Here's the list of armor a red wizard can use that a white wizard can't (using NES names):
Wooden armor
Chain armor
Silver armor
Buckler
Silver gauntlet (red wizard only)
Zeus gauntlet (red wizard only)
Power gauntlet (red wizard only)

White wizards have only one piece of armor red wizards can't use, the white shirt.

The chain armor is the reason people think red mages are good tanks: it's the best armor available in Coneria by far, and is only usable by fighters and red mages. However in terms of armor that's better than what other mages get, that's it. Their next unique upgrade is the silver armor, which is slightly better but doesn't become available until you have the magic key, at which point you've also found silver bracelets. Silver bracelets are available to everyone, have the same absorb as chain armor, but have a much smaller evasion penalty (even than the silver armor). Basically, once you reach this point, red mage armor goes from way better than other mages' to slightly better than other mages'. Once you get the airship, you can get gold bracelets, and the red mage loses any body armor advantage.

The buckler is a legit win for the red mage, but it's worth only two absorb, and in the very long run is replaced by the ProCape anyway (and anyone can use those). The various gauntlets are another interesting case. You can (and should) get the better ProRings as soon as you have an airship, while the gauntlets require the class upgrade to be used. They may see use on a red mage for their abilities (especially if you're playing on an NES where inventory space is at a premium), but they're never a defense upgrade over other mages.

So in conclusion, red mages have better armor than other mages, and in fact every other class in the game except fighters, up until you finish the Marsh Cave and defeat Astos. Which is a part of the game a lot of people remember because it's such a pain. But it's less than 1/4 of the way through the game, and after that point red mage armor is essentially the same as any other mage. By the time of the class change it's identical.