General

Drks (or maybe just me) are so weak the stupid SD is 'somewhat' worth getting cause it hits bigger numbers.

Might not be the case for you.

Hi Ed

OT: It's really not worth it unless you really want a skill that you can brag about. It's not for damage; it's just a flashy skill you use when you're bored.

[quote=dubmason]The drop rate is insane... but is it really worth it for soul driver? Do you get anything else from completing the quest?
Thank you [/quote]

You're not halfway done yet even after completing Lunar Dews. It's not worth it for soul driver since you already have access to superior 4th job skills.
Soul Driver is more for its "looks." or sense of completion by having access to all skills on your Adventurer.
Here's what happened when I Lved Sharkwave to LV 5 on my buccaneer. Note that I did all of these on 8x/6x/4x drop. I [b]never[/b] hunted during 1x.
Lunar Dews: Difficulty: Extreme-Hell (Need 20)
Earth-Cleaving Lightning Part 1: Difficulty: Extreme-Hell (need 10) I went to Ultra Grays
Earth-Cleaving Lightning Part 2: Difficulty: Medium (need 10) I went to Cube Slimes
Earth-Cleaving Lightning Part 3: Difficulty: Medium (need 10) I went to Pandas
Earth-Cleaving Lightning Part 4: Difficulty: Hard (Need 10) I went to Bone Fish
Earth-Cleaving Lightning Part 5: Difficulty: Medium (need 10) I went to Hankies
In your case, You'll be hunting Soul Lights instead of Earth-Cleaving Lightnings because you're getting Soul Driver

It is not worth it if you are looking for an extra skill to boost your dpm. The only reasons you should do this INSANELY hard quest are:

You like doing quests.
You like grinding as a challenge.
You like having a flashy new skill that others won't have.
You like being that special little butterfly.
You like bragging about how you're COOLER than UA's and how your character took more dedication. (Because face it, getting to lvl 120 on a KoC and then training an adventurer to lvl 120 would be about 10x quicker than doing these quests.)
You like hovering over a computer killing the same monster for hours on end.
You want to macro a skill, like me, and have it say "Not a UA Foo"

Edit: Also the lunar dews don't give soul driver. They give empress's might which lets your wear equips 10+ your lvl. Soul driver is a whole new quest in that quest chain. It goes 20 Lunar Dews (Empress's might) -> 10 Flashing Lights (idk what they are called) (SD lvl 1) -> 10 more blinking lights (SD lvl 2) -> 10 super flashy lights (SD lvl 3) -> 10 Kanye West Music Video lights (SD lvl 4) -> 10 Seizure-inducing, but can't ever look away lights (SD lvl 5).

It is estimated that one could achieve lvl 180-200 by the time it takes to finish these quests.

When you mean insane, you mean hard to get right?

You're already at 4th job, and IMO Advanced Charge and Blast should outweigh it by far.