I don't think any grade 5 nodes have 50+ mobs near them other than the NMs but I thought they moved the nodes away from those.

I do wish they would have kept it consistent with Prospect, Lay of the Land and other such abilities however. Will be odd getting Coeurl Step IV when you get Lay of the Land V. It sould have been like this:

Coeurl Step I
Learned at level 1. Renders you undetectable by enemies level 10 and below.

Coeurl Step II
Learned at level 8. Renders you undetectable by enemies level 20 and below.

Coeurl Step III
Learned at level 18. Renders you undetectable by enemies level 30 and below.

Coeurl Step IV
Learned at level 28. Renders you undetectable by enemies level 40 and below.

Coeurl Step V
Learned at level 38. Renders you undetectable by enemies level 50 and below.