You don't have to worry much about martial trance stopping you from fleeing.

It may also reduce the offense boost of martial trance but I can't be sure and don't think it does.

I've had it on numerous classes.

In particular it was one of my most useful edges on Tsalantha the ap. Because having a flee blocked can easily be lethal if your tanking is poor.

Would I get it on a conjurer? Possibly, but conjurers have a lot of other useful edges, so probably not.