Well, Heinlin/Leviathan is now somewhat terrifying in the early game. Or maybe I just have bad luck. I decided to fire up a test game, smallest galaxy size, only 1 other empire.
On one side, I have systems with heavy crystalline presence. Including some sort of nexus thing. My first corvette scout fleet jumped right into the middle of a 1.2k-strength fleet and died before I could retreat.
I rebuilt, eventually. Gave the new fleet an admiral. Went exploring in a different direction. Encountered the only other AI empire. Exploration in that direction is basically pointless now, unless the AI empire is friendly enough to allow open borders once we make contact.
EDIT: Contact made, despite being fellow xenophiles they immediately close borders. How nice. Also they are militarists and I decided to go pacifist. Extra nice.
Traveled in a third direction. Encountered a pirate haven with a 6k+ fleet hanging out right on the near edge of the system. I lost my second fleet along with the admiral. I don't want to go anywhere near that, so a third direction of travel is denied to me...and if the massive pirate fleet decides to come snooping around I have absolutely nothing to stop them. Shit, I just got ion thrusters.
EDIT2: Bad luck, I guess. Science ship critically failed an anomaly, resulting in the loss of the ship and the 4-star scientist on board. Now pirates are attacking, I have no fleet, and I lost yet another ship along with a valuable leader. What a fuggin start.