The best upgrade for you is truly going to depend on the skill of your DPS, and the amount of gear that drops for them in your coil run. 3 Weeks in (we started playing in late Sept. We were way late to the party! :P) we've seen maybe 4 DPS drops. Out of those drops, I think half of them were for our Dragoon (OF COURSE!). I still have no problem holding threat. I can see that changing dramatically - especially on Turn 2 if you take the slashing debuff route and have a ton of piercing damage (Our blm and smn both switch to bard when we take the west route). I've found a fun way to test your threat is to do AK with your 2 best dps and see at what point you can AFK on the last boss and go make a sandwich!