Why is mp recovery useless?

I really regret putting points into MP recovery instead of Barrel. Barrel is what makes pirates useful on GPQ, and that means alot if you are leading GPQs for a small guild.

Isn't using barrel to walk pass the golems too dangerous since it has a 10% chance of failure when max? I believe barrel is used only in desperate situation where you cant get a thief with dark sight in GPQ.