Thought of the evening: No matter how mighty your fleet, how nigh unstoppable your attack... you will occasionally walk into a devourer golem.
And there goes 1.6 million metal.
Observations of the update, mostly: Bomber starships are brutally powerful. The lowest tier is what, 300,000 something attack power? Fittingly the AI likes to target them first and they are anything but cheap. They're fairly durable but when an entire planet decides to throw itself at one, it WILL die. A few mark 1s and mark 2s an wipe out a fortress pretty readily, as though it were never there at all.
Eyebots are a really interesting type of ship. Essentially fragile scouts with high attack power. They don't fit into your fleet very well-- I've used the entirety of tier 1 and tier 2 to wipe out a low level AI planet, but they can still hit a minefield or a flak turret and all vanish in a puff of smoke. They are, at least, cheap.
Shield Bearers (or Forcefield Bearers?) are unexpectedly useful. It seems like the logistics of making sure their shields cover vital ships would be painful, but with enough of them everything straightens itself out pretty intelligently. And they soak up a lot of damage.
Normally I take Riot Control Starships primarily. However, Flagships and Zenith Starships are very useful too. The attack power boost to nearby ships is of course amazing but it seems (especially with the update?) they're pretty terrifying in combat themselves. And very very durable. A Zenith with a fleet of bombers will, of course, pretty much double their effectiveness which can help you deal with the limitations imposed by unit caps.
A tip I didn't realize until far too late: scout starships, which are available at start, counter enemy snipers. This is amazing.