The only pull size is the one you are comfy do not ever put yourself in a position were you are biting off more than you can chew because you have some impatient players. The opening pull take 2-3 packs ~ 9 mobs and work how long it takes you to kill the lot. If they don't seem to die quickly and the healer is now looking like his/her hands my explode from sheer casting of heals on you, then that group can not handle large pulls end of, you revert back to 1 pack and continue that way.

You should also tell by party make up if you will be able to get this done in a multi pull run, if you have 2x Dragoons then no, your wasting more time dealing with large pulls. If you have a SUM/BM with a RM sure go wild both of those casters are not going to be in the way and can use AOE.

Remember DPS that require themselves to be positional for their attacks can't do shit when they are having to move around because you have that many AOE angles to avoid.

Also if you are going to run and do multiple pulls to get the clear quicker take an healer you are confident in.