Man, I was having another great run with the Carnelian--got two Scrap Recovery Arms early on and had a zillion scrap by Sector 7--and the game crashed on me. Ugh. I was totally going to beat the Rebel Flagship, too.
So then I thought I'd take a break from Crystals and try the Stealth Cruiser instead, since that's now the only one whose alternate layout I haven't unlocked yet. No luck, though: I keep dying. Nesasio starting out with no shields is real rough. The cloak helps a lot for dodging the first volley, but it's useless against beam weapons, and past the first couple sectors, trying to keep their weapons down with dual lasers and a mini-beam can be a hopeless endeavor.
My hope is to make it to the last stage of the final boss. If I can manage that, I should have the "Avoid 9 damage in one cloak" achievement in the bag by dodging the power-surge attack. But it looks to be easier said than done.
I also have yet to unlock the Slug Cruiser or the Mantis Cruiser, which is sad, since I really want to try them out. I know the Mantis one is about boarding, and I doubt it'll be much better than Carnelian, but it could still be fun. And with the Slugs, I really just want to kill their crew with Fire Beams or Anti-Bio Beams or whatever sadistic crap they got going. (And the telepathy ability is neat.)