Quote Originally Posted by Jeeqbit View Post
It really doesn't matter, but if you change over then you have to level the other class to the same level as your MSQ and put some gear on it which may be inconvenient.
This is only an issue for ARR/HW jobs. For Stormblood onwards (so including red mage) the jobs start at the same level as the quest to unlock them and give you a decent set of gear so there's no delay in switching job and continuing with your MSQ.


Quote Originally Posted by Rongway View Post
During the catch up expansions, the main story throws so much xp at you that you might be able to level both PLD and RDM side by side and never reach a level lock in the MSQ. Even if you do reach a level lock, a couple dungeon runs as each will get you over that and ready to continue.
This too. Quests give a lot of EXP and the levelling roulette will give you a nice boost if you're not keeping both classes up to speed.