I see the downside of Augmented Engines worse than Unstable Injector. Engines are going down after a good hit regardless of four times damage or not. At that point, repair time matters more, and it is forever with Augmented Engines. Unstable Injector also have the acceleration benefit that Augmented Engines do not have. Simply put, Unstable Injector is superior to Augmented Engines in every way.
Despite the heavy OP cost, I use Unstable Injector with *every* ship except Hyperion.
I would like it if Augmented Engines gets better, whether less OP, no downside, more acceleration like Unstable Injector, or... something.