I was referring to the Despoiler with 3 Lances, 9 torps and 6AC, which easily beats the Emperor.
AC on LCs isn't so fantastic, as a wave of 2 can barely be depended upon to survive turret fire, just 2/3rds as effective as half of a wave of 4 against a T2 target. They're almost purely defensive. In addition to being just less effective, it's a more expensive way to spam ordnance by taking Enforcers or Defiantss, as they're both more than half the value of a Dictator.
The Tempest IS cheaper per bay, but you get a lot less for your points. For 180pts you get 4AC, 4 hits and 8WBs. The Dictator for 30pts more gets 4 more WBs, 6 Torps, an additional shield, 4 more hits and an additional turret. In addition, the Tempests absolutely MUST be in base contact to launch an offensive wave, because a single bomber is going to die to turrets 75% of the time.