I think the really mean part about the Lilith is that, despite that beam cannon being REALLY ****ING HUGE, it is somehow blocked by the ships structure when you face that cruiser from the front. I always have to dive under it in a very certain angle to get a clear shot and take out the cannon. This problem is not present on the Cain...
I have now beat the mission twice on Easy, both times with the Myrmidon, 2xKayser and full Trebuchet loadout.
1 Treb for the Cain beam cannon, 4 for the Lilith (because the first salvo never hits right), the rest for the Ravana.
I will wait for the voice acted version of the campaign to be released and then play it on Medium.
BTW, I finished the campaign yesterday for the first time (in one playthrough because I started again with the 3.6.10 version) and was totally blown away. Nice job on all fronts... the ending really hit me hard.