I did some tests as DRK, and from my findings, 21 DET was superior to 6 STR, but inferior to 8 STR...
Then I did some comparisons with a piece of gear with +9 STR, +27 DET -51 Crit. Welp, I was critting more with this setup and still doing less on my minimum damage values than with a setup with +51 Crit, -9 STR, - 27 DET.

So, not too sure about the DET nerf to auto attacks, but what I found out is that crit is reaaaaaaaaaalllllllyyyyy weird.

Even during hunts in full parties, with 'real' dps jobs... Or in Neverreap rush parties... People would just hover between 7 & 11 % crit

Crit seems really useless.

I saw some abilities randomly critting for +40% damage, some for +60%... o_O

About Skill Speed & Spell Speed, they apparently now allow dots to deal more dmg? Otherwise they don't affect the cooldowns much more than it did in 2.55 , still need A LOT of SS to reduce the cooldowns under 2.40 sec