I tested this against PVE mobs outside Jord. Formula seems mostly accurate assuming you have no dmg variance for missing spec and item bonus. I did not add in option for relic bonus. Welcome to Midgard I guess?
Some notes I found:
1) The formula I found online stated bonus to spell dmg from primary casting stat was (1+Stat/200). I found this not to be the case it seems like it is (1+Stat/250) meaning a slightly less return on primary stat increase for dmg.
2) The multiplier for + Spell Line in gear is still (1 +Bonus/200)
3) Changes to WP drastically reduce return for PVP, some optimization tests with with a similar spread sheet in excel found going a route of mostly MoM with some Aug Acuity improves average dmg output. If random burst dmg is still the goal WP still has a role to play obviously and a couple of points in WP does have some early returns.
Hope it helps some.
Edit: Disclaimer, I did not test with buffs, not sure if there is a soft or hard cap to Dex or Primary Casting stat.