1) The new damage model is awesome. Frigate combat has never been better.
2) I don't mind that SOLs are tough, almost impossible, to sink. It is as it should be. Bigger gripe: They should be relatively rare, insanely expensive to maintain, and treated by nations like crown jewels. Keep it as-is.
3) Boarding (or, boreding) is dull and ahistorical at present. I don't mind the rock/paper/scissors part of it; I didn't buy this game to ram people and play a minigame, then pretend I am a competent captain. Right now, rage boarders can one- or two-shot a massive SOL. There's no way that should be happening.
Nerf Marines along with all boarding upgrades. Not saying there isn't a place for boarding, but it shouldn't be a substitute for actual combat, or combat skill.