User blog comment:PantherRH/Divina Observations/@comment-86.27.122.26-20130303190959/@comment-6595135-20130304063535

Yep, skills change the picture a lot. The ER is only good if you have two similar daemons in terms of ATK/DEF and skills, and their spirit required is roughly the same or close enough for you to debate using them as a matter of choice.

Then again, according to the numbers, there are some obvious discrepancies that have no logic in their design, such as Diaochan having a rather high DEF ER (1.27) but with an offensive skill (reducing Divina defense).