So I'll admit, I don't often use the ISD I, I like my 8 dice at medium and provided defensive retrofit slot too much... but I want to understand the ISD I better.

While I can see both Relentless and Avenger being effective on the ISD I (even though Avenger was an ISD II) Devastator seems like a counter intuitive title for it.

I considered the value of having an extra blue for accuracy and using H9s, I also considered the value of extra damage via sw-7s by late game, and even getting rerolls with leading shots without cutting from your base damage.... but all of these seem fairly under powered on a ship that (supposedly) should be taking Vader and can take OE for black dice...

Am I missing some upgrade that ties all this together?

Never thought about it, but somethings that come to mind : Using Vader + Needa + TRC to improve firepower, while also providing blues for future rounds

But I agree with you, they don't really go well togheter

I've been looking at Devastator for a week or so and am going to try and make it viable. Right now, my next plan to test is ISD1/Devastator/FC/EHB in a Screed fleet. Basically, a supercarrier that careens in right behind the squadrons.

Screed seems the commander for an ISD 1. The odds of 1-2 blanks are good with 8 dice. Though Vader seems the commander for Devastator.

I took Vader in Correlian Conflict on the Devastator. I did succumb to my teammates insistence that I ISD2 it though on the grounds that according to the fluff Vader'a Devastator was so heavily upgraded as to almost be an ISD 2. So... Thanks to Intel Officer (kill my own tokens!) he rained down firey death in the All Out Offensive when he hyperspaced in and killed two MC30s right off the mark. By the end of his second activation he had four ships to his name. Such Rogue One-ness!

It seems more valuable if you expect to lose tokens before you start running out of targets. I've had ships with no tokens at all by turn five, although it's rare enough that I don't really factor that in when list building. Devastator seems a little expensive next to the other titles, and honestly I think Avenger is more worth building around. The overload Pulse combo is pretty clunky but even just dealing enough damage to tempt your opponent into bracing works with Avenger. Devastator is more than twice the cost and doesn't provide that much more offensive power than Avenger.

I may end up useful agains MSU fleets