Just keep rule number 6 in mind. And if a ship is genuinely OP, I'll probably won't finish a run with it.
Well I'm not too certain about how OP they really are. The Etwhal's guns simply won't manage past the early sectors. Sort of like the DA-SR12 or the Red-Tail, the loadout is powerful early on but it lives on borrowed time. And you should really check out the artillery. probably not useful in later sectors because if you can take down shields, you can take down the ship just as easily but it's pretty... so, so pretty.
^ I'm doing a run in CE Infinite. Thanks to a Pre-igniter I found early on, the run simply is firing Burst Lasers at the shields, followed by the Crescendo. It really wrecks up empty rooms well
With the Demacian Justice Cruiser, the infinite ammo Energy Snare bombs can be used to lock down a single system (provided none of them miss) so you could stop a ship from firing before you bring in the Final Spark, but you only have two weapons slots and you have to put up with Lux's laughter all the way through. Overpoweredness has a very annoying price
EDIT: Of course the ultimate test to see if the ship is OP or not is after spending 3 hours on a CE Infinite run, not buying everything and then getting your butt handed to you on the Flagship
Yeah I can never really win against the CE Infinite Flagship.