Tell me the mandatory GL losses that aren't manageable by keeping PB ready for it. PB gives you 3 GCDs to get back up each GCD faster than the last, DRG needs 4 normal time GCDs to get back into the rotation. (I'll agree you should wait B4B out so you don't waste it, thus was a moot point on my end)
Getting rid of rng losses, T10 is 100% uptime, T11 is 100% uptime, you might lose it once on the transition to bennu phase on t12 and you'd lose it on the jumps in the last phase, but again once you're built up, the damage from a monk is steady plus you'll have at least one PB for those losses. T13 is lost at the start of the add phase and your group should be leaving a gust up for you to maintain stacks going into the last phase.
T12 is the only fight where monks can take a significant hit however, since you also mentioned the current ilvl of players, you shouldn't see that second jump. Falling back to my previous post these fights are long enough that the sustained monk damage shines. And this point about DK and mantra being useless is really moot, you people are making it sound like your group wants to kick you now that everyone's geared (spoiler alert: megaflares still dickpunch you real hard with only storms path up).
EDIT:
since it's already been said I'll just add the quote here:
