Not trying to rain on your parade or anything like that, but I think the DPS should just be left to the DPS, with anything coming from tanks/healers as "icing on the cake." I mean it's nice that with that setup you get around 1k-1300 buffed crit, but a firestarter gets me a little over 1100 on a normal atk with crits ranging from 1400-1800 in simple 4 man parties.

In coil or any fights where there can be quick big dmg atks to the tank, i'd rather have a tank that is focused on staying alive/making the healer job as easy as possible vs one trying to be a tank/5th DPS. Just my honest opinion.