Backblow. Anyone actually use it?

As a summoner, I can easily get behind a mob to make use of this SA, and it seems like it would be a good SA for a mage who doesnt get any critcal passives. But has anyone actually used it and tested where behind a mob it goes into effect? Is it critical you are *exactly* behind a mob, or a couple of degrees off is ok?

And you think getting the lowest C with backblow (which would give the highest + to critcal) makes more sense then getting the highest B with backblow (gives -20 less to critical then the lowest C)? Of course the patk difference is big, but if I crit more often (I have +4dex and lvl 60 pp buffs), I'm thinking it sould offset the difference in patk over the long run. Comments please. :eek:

The advantage in patk is going to make more of a difference than a few points of crit rate. The b-grade will definitely do a lot more damage. It won't even be close.

I had a friend that used a back blow dagger on his 2-box and he loved it; you don't have be exactly behind the mob, you can be off a bit.