If I play one job through the entire 6.0 MSQ. Would it be tough to gear up another job(s) for high-end side content?

I've read a speculation that ilv 510 gear should be able to get you through 6.0. Does that mean I don't have to worry about grinding and gearing up when questing through 6.0 main story?

I ask only because I want to save time and still couldn't decide what job to play through 6.0. Certainly I'm convinced to play PLD but I ain't a fan of its actions and its, with all due respect, terrible job backstory.