Your first post has pretty anything you have to decide. Choose from hard OGCD management and Position+Uptime management, and way to go. You need to take care with this type of thread cause ppl usualy feels that their Jobs is somehow "better" if its harder to play, so sooner or later this kind of thread becomes something like "My job is harder and better than yours".

I would only add two infos here about my experience as DRG. First, is the Jump management. It's frustrating how you need to use it to max your dps, and sometimes it'll just kill you. Like t11 (specially add phase), t13 (Megaflares), some primals, etc. This is the only thing I actually feels "hard" as Drg, as you need to know each second of the fight to predict mechanics and even those sometimes vary depending of the party DPS and the relation with the boss mechanics triggers. The rest is muscle memory like any Job.

And to your other question:

"Which one is more demanding than the other?"

As the 2 classes DPS is somehow close (won't go in this merit), MNK has the valuable Dragon Kick wich is highly demanded in early contents, while DRG "only" buffs Bard DPS.