I love the Defender, even as-is, although I understand why it's claimed that the ship is overcosted. The Defender is the ultimate jousting ship, and if jousting values say it's overcosted, I can't really argue with that!
I like the idea of a green K-Turn, it's a bit funny but would really adjust how I'm willing to fly the two unique pilots; suddenly an Engine Upgrade and Push the Limit are no longer antithetical to how the thing flies! Flip around, Boost or Barrel Roll then focus, then flip around and do it again. That essentially gives it a SLoop if it's warranted, and a good ol' TL/F any other time. Normally I can't stand fitting an Engine Upgrade on there because you have to lose Focus or Target Lock just to make the thing fly more like a TIE/ln or Interceptor, and that's not in line with the ship's dial. Also, it's going to be a little difficult to repeatedly stress out the generic pilots to make the change worth anything.
I don't see FFG trying to fix the ship by changing the dial. I feel like the R2 Astro and Unhinged Astro are slightly different cases, in that their application and opportunity cost weigh in appropriately for the few ships that can use them. The Defender has a solid dial; I've never had a situation where I thought the maneuvers available to me were problematic. The thing handles very differently to everything else, that much is obvious, but I think FFG really nailed what they were going for. The bread and butter basics are:
4-K white
5-straight green
3-turn white
1-bank white
and very rarely do I need to pick something besides those four moves. Vessery and Brath have a little more leeway because they move later and might need to pick a 2-bank or 3-straight to remain unpredictable or on-target, but that's what happens when you're hunting ships with lower Pilot Skill.
In my opinion, the Delta Defender is one of the strongest ships in the game, and has a lot of potential, but is completely ignored due to cost, dial, and Phantoms. I don't hold it against you for not flying Defenders, that's not an issue, rather I wish people would give it more of a chance to do what it does best: barrel straight into somebody, blocking at PS1, then following up with a white K-Turn and raising hell. Phantoms are harder to do this to, and YTs aren't all that bothered by having you behind them, but in both cases if you can grab your focus token the Defender is a beast to put down. This isn't exactly news.
As for attempting to fix the ship, if FFG does give it a unique Title or Mod, I hope they're as clever and unpredictable as they have been so far.