On your FC leader, being that he is the one suggesting it, if others start to vent he should be putting them in their place anyways. His idea and all that.

As for practice before then, I actually suggest Ifrit EX. Even with overgearing you still want tank swaps outside maybe your FC in very good gear, as each stack Ifrit puts on a player reduces their hp on top of making them take more damage. On top of that managing your cooldowns especially during nails with stacks since they explode on this version, when to use hallowed, when to provoke since sometimes its actually better to let the current MT take an extra stack since Ifrit jumping could ruin your provoke. Plus you can go for the pony while practicing!

Can't really say anything on Coils since I can't do FCoB yet.