Id generally agree with what has been said thusfar:
The Centauri as a whole are not broken.
The Primus is nasty but fair. Same for the Maximus. I'd actually say the same for the Corvan, its one of the nastier patrol ships but not still perfectly fair in my eyes.
Now we get to the problem ships:
1) The Sullust. Now I'll start of and say the Sullust is NOT broken. It is perhaps a tad bent... It has a HUGE amount of firepower for a raid level ship but no worse than many others (though most of them dont have it as beams with forward arc...). The issue with the Sullust is rather that for a heavily armed ship with good range it is possibly SLIGHTLY too tough and could do with losing some hit points. Used sensibly its still fair though in my eyes and only starts pushing it a bit when used en masse.
2) The Prefect. Now this is REALLY pushing it. Even MORE firepower than the Sullust (which is already treading a fine line), and the loss of a couple of interceptors is MORE than made up for with the increase to hull 6. The prefect is certainly beatable but most people agree that it is simply too good and shouldnt be used much (or at all!). Certainly taking multiples of them in a relatively small game would be considered blatant powergaming by most!
3) The Tertius. Basically a bigger Prefect. Again its can be beaten but it simply has too much firepower to be fair. Most races WAR level ships can only just about match its forward firepower! (or VERY slightly exceed it). NO races War level choices are a match for two Tertius in my oppinion. Not even close.
Overall I'd have to say Centauri ARE a perfectly fine list AS LONG AS YOU:
Dont use Tertius or Prefects
Use Sullusts only in moderation
Keep to these simple rules and I think you'll find your opponensts not only complain less but you yourself will enjoy playing Centauri more too
