As to the necrons, I feel a total rewrite is necessary, as they are balanced too far on the extremes. Like stationary lances, which I proposed in my alternate rule-set. However, going on current rules, the escorts could use a 5+ save. Currently, Necrons are easier to damage than shielded ships, which is sad.
Why do you think the shroud needs more hit points? I always took it as just being a very small, stealthy capital ship.
For the nids: I feel the kraken can be overcosted. I feel the stalker and vanguard droneships are too tough. I feel nids shouldnt be able to teleport.
I feel the Razorfiend should be 10 points cheaper and 15cm, with built-in option to take solar veins.