Back in my college days I had this concept that if the many-worlds interpretation of Quantum Mechanics was true, there must be some world (or indeed nearly infinite worlds) that all of the accidents of time travel and faster than light experiments from other realities must end up in.
Now imagine if the powers that be in those worlds start collecting all of the different technologies that other realities rain down on them and start assembling a juggernaut of all the good ideas from all possible realities, combined. They, naturally, would ignore all of the Faster-than-light gear (because they know ultimately what happens) and instead focus on all of the power generation, sublight propulsion, computer controls, weapons, life support technology, and so on. Any prototype light speed vessel is probably a normal ship that they bolt a hyperspace drive onto. Or if it is custom built, it needs the most cutting edge control systems to keep the crew size low.
Except, of course, that there would end up being multiple "Best of all world" realities. Technology is a bit of a formless thing, until you start cutting steel plates and trying to weld them together. Then you pretty much have to have a single design. Same with power generation, propulsion, tactical systems, life support, and so on. Having 80 technologies at your disposal is no good, when in the end you can have one and only one running on a ship at a given time.
The Engineers in these realities would probably find that there are multiple clusters of technologies that really only offer dividends if you are trying to express one aspect of vehicle performance. A long range spacecraft needs one kind of life support and propulsion system. A high speed interceptor needs a completely different set of both. There is some off the shelf technology the two can probably share, but the fundamental design is dictated by the ship's ultimate function.
Tradeoffs would be determined not by performance but by cultural preference and the dictates of logistics. Yes, anyone could build the ultimate battleship. But generally all they need is a little frigate to make a show of force and keep piracy from becoming a profitable endeavor. One giant battleship can't patrol multiple areas of space, but a fleet of smaller craft can.
On the other hand, a tiny frigate against a battleship would be an extremely lopsided battle. Battleships can support massive shields and armor. Yes, a Frigate might have torpedos that could penetrate all of that, but a massive battleship can actually absorb that much damage and keep fighting. A frigate would be vaporized by an equivilent blast.
Whether your fleet is built around large capital ships, or swarms of smaller vessels would largely be determined by your industrial capabilities and the amount of territory you have to cover.
How this ties into Iliad-07 is this. Iliad-07's universe is where attempts at time travel and hyperspace from our world end up. So imagine if in Back to the Future, Doc's car simply vanished and never returned? He would end up on Iliad-07's version of Earth, and first off people would be shocked at this horseless carriage. Then you would have this guy with a crazy look explaining about airplanes, and time travel and... he would probably be in a psychiatric ward within hours. But after scientists analyzed his car, concluded the parts were made with processes that are unknown in their world, and the stainless steel used is of a novel chemistry that is not mass produced anywhere, they would be forced to deal with the fact that they live in a multiverse.
In our world, people are deathly afraid that setting off on a decades long trip would be for naught if some time after they left mankind uncovered the secret to faster-than-light travel. In theirs they know that even if you make it work, you end up on a one-way trip to another Universe. To see the stars, they know there are no shortcuts. Or, maybe there are shortcuts, but it requires towing the portal out to the destination first the slow way.
We don't know this information in our world because all of the crackpot inventors who manage to unlock the secret lose their probes to seeming oblivion.
Which of course means that I need to throw in a few Bermuda Triangle, Philadelphia Experiment, and Amelia Earhart references into my lore.