Yep, two Fighters and two Red Mages is a very good party. I tend to use a more defensive approach, though, so instead of having two Red Mages, I usually have a Red Mage and a White Mage. That way you'll get better healing spells and Dia/Harm spells too. Red Mage will help you as an additional healer, and he still has enough black magic to destroy large groups of enemies. And the spells Haste and Temper. Besides, by the time you get all those spell-casting items, it doesn't really matter any more that Red Mage has less MP than Black Mage.