Yeah, and functionally the Road to 70 buff means that you don't have to optimize for experience gain and leveling - simply completing MSQ (incl. running the required story dungeons) brings you well beyond level 50, without the level gating and dungeon grind you'd otherwise have to face without RT70. So it both makes the routing simpler and brings the overall run duration down to a more manageable level (though still quite lengthy) for a single segment run.

Yeah my understanding was choosing CNJ/WHM simply for healer queues. Also in my opinion, healers have the most variable dps contribution to dungeons/trials (ie. the difference between an actively dpsing healer vs non-dpsing healer), and that can add up over the course of the run.

I learned a lot from the runs listed on the leaderboard, and I have a couple recent runs on Twitch at ~15.5h (one SS, one MS; both yet to be verified) if you wanna check those out as well. Sounds like you've got a great plan though, best of luck with the run!

Tons of fun, and there are a handful of people doing it! I just ran/streamed it yesterday, and today there's even a co-op run going on right now (deln, dragonkick2, matthiagryffine, xelnaphon), which seems to be a test/experimental run for co-op. They're going WAR/BRD/BRD/WHM - check it on out stream as well!

For the run itself, did you check out the rules? Preferred server/RT70 allowed (so essentially required for that category), no marketboard/trading, no moogle delivery, and if you're running solo no premade parties (solo queue in duty finder). Different categories are available for single segment and multiple segment runs, so do what suits your schedule/lifestyle, don't feel limited to trying it in one go!

Beyond that, think about where you want to fit in your class/job quests alongside the story quests for optimization. It seems that's the main consideration in the first part of the run (before 50). Later on, we need to keep in mind completing the three HM trials (Ifrit, Garuda, Titan) and the three alliance raids (Labyrinth of the Ancients, Syrcus Tower, World of Darkness) while completing 2.1 - 2.55 MSQ quests.

Hopefully that helps at least a little bit, feel free to ask some more follow-up questions!