Maintenance for the week of January 12:
• PC/Mac: No maintenance – January 12
• ESO Store and Account System for maintenance – January 13, 9:00AM EST (14:00 UTC) - 12:00PM EST (17:00 UTC)
Around 40CP is where you see your biggest gains @15%/25%, after that it's kinda dead - As for Khajit in specific, I'd imagine building flat damage is still better as you don't have a high enough Crit Chance to make it worthwhile, also flat damage scales with crits.
Assuming this is PvE based it's easier for you to test alone:
Hit a dummy with current setup (Unbuffed is easier to manage) - Record familiar Crit and Non-Crits with a few abilities.
Take out X points from Y(Thaumaturge, Elemental Expert, etc) and test for the same white and yellow numbers
Add those removed points to Elfborn and test the same values again
Compare and adjust based on what you're finding until you have an answer.
There's obviously more depth to the math than just eyeballing it like that, but you'll get a rough idea.
vMSA - Magplar - Xbox EU - 15/11/16
578,000 - 36 Minutes 58 Seconds (Top 2 World?)
vMSA - Magplar - Xbox NA
569,000 - 40 minutes (350CP, Non optimised runs)