I'm no MCH, but I think your dps would profit more from crit than SS considering the auto-attack of your turret isnt affected by it. Having too much ss also mean you are having less crit and det, meaning they are hitting less by default. Crit is also very good on MCH considering the fact that you have a Auto-crit move much like Dragoon's Life Surge. So I think you would benefit more from having more crit than SS for base damage, but also for Wildfire. In your opener, if you have a dragoon near with Battle Litany, your crit rate is going through the roof, and critting everything in your Wildfire means you get pull a really huge amount of damage.

But again, I'm not a MCH.