Expertise.
I'm not really blown away by either the TIE Striker or the U-Wing. I don't think either of them are bad ships, but with so many other ships to compete with they just don't shine above my top choices.
But Expertise is an amazing upgrade. It basically mean you never have to take a focus token for your action. In other words you can free your action for repositioning. It also makes ships like Rey/Finn that already get re-rolls really deadly without any actions at all.
It would almost be an auto include except it is competing with some pretty good EPTs. I have been preparing some Defenders for Regionals two of which had Predator and Ion Engines. So I had the points to change the EPT to Expertise, abut I decided in the end not to. I pretty much spam focus actions when I am not barrel rolling with my defenders. With the x7 titles I get focus evade most turns. I really like what focus can do for defense. If Expertise as a weakness is it means that if you don't have the evade action then there really aren't any good defensive options. Sure you can still take focus for defense, but it isn't as good an option if you already have expertise.
Don't get me wrong I think there is a pretty good chance that from now on I will at least consider Expertise on every ship that can take it.
I am a little worried that Expertise is just another boost to offense leaving two attack dice ships really outgunned.