been playing Imperial Navy alot recently too. found them sofar to be terrifyingly powerfull. As long as I have a decent ally in 2v2 we have been steam rolling everything.
Taking 5 dauntless mark two and a stealth upgrade has been my favored deployment so far. Fast enough to rund down the druchi (dark elf) stealth battleships. Possibly going to swap one LC out for a pair of escorts for their mark ability
Thinking on wheather stealth LC carriers might be effective. or a dauntless 1 stealth torpedo spam.....
As for the space marines cant understand the builds I'm seeing. a single battlebarge would seem to be entirely the wrong idea on a 2v2 map.... The more LC or CA, the more times boarding can be spammed at a critical target.... kite with fighters to drop turrets initially, after boarding craft are up, close under burn to deliver boarding craft followed by boarding action both of which penetrate shields, boadside till shields drop and deliver space marines special ability board...... should with proper setup be able to deliver 3 boarding actions from each ship, 9 boarding actions against an enemy warship a reasonable expectation and deliver 6 of them within seconds of eachother before his shields have dropped.
necron do need their special teleport movement to be much more readily available... may long charge time but store charges based on ship size?? This would allow them viable defense against massed Nova attack