Can Someone Explain

[Lyrinn]

Supposedly 1 MND = 3-7 DET, depending on which source you read. Maybe some of the mathcrafters can come in and explain how that works.

In general, DET is just an all-purpose stat; you can't go wrong with stacking it on any job. If you're looking to boost your DPS, DET/CRIT is the way to go (and ACC if you're not at cap, of course). If you're more interested in the healing aspect, do whatever you want because none of the secondary stats matter enough to make a difference. Keep weapon damage and mind at appropriate levels and you can heal anything (and yes, you can heal T6-9 with your gear; I solo heal most of it with worse gear).