Unless things have changed since the last time I played, building frigates and escorts just to deal with pirates is entirely counterproductive, since pirates get your designs for free. Thus, you lose again, because your ship doesn't actually outclass the pirates anymore. What's more, the thing you were escorting has decided to do a moronic rabbitrun instead of simply ignoring the little pests, and now won't be making a delivery...so I don't bother equipping them with shields or armor, either. Just let 'em blow up. At least then they'll finally update to the new version when they have to buy a new ship. Plus, making them buy a new ship makes me money.
So basically, I just don't ever build frigates/escorts/destroyers/cruisers. I build armed dropships and capitals only. I don't really use carriers, because with fighters having a pitiful speed of a mere 130, my ships go faster than they do! Besides, the arbitrary space requirements of carriers renders them largely unusable: After you've tossed in the required 50% engines and turning on top of the 40% fighter bays, there's just nothing left for even basic things like "Reactors", "Fuel", "Shields", "Armor", or "Weapons".