We don't have enough Choirs to spam them, so we want them to have a higher innate toughness. Doesn't matter if we can build 4 per action if we can only actually field 3 total.
We don't have to build 4 of them tho? We can mix and match designs within size-class for ships as much as we want, we just haven't have a need to. We could build 1 Pathfinder and then 3 of whatever combat destroyers are most needed whenever we needed a new one to go with a free Choir.
And to be honest, we never want these ships to come under fire at all, if they do, we're already in a losing situation, so having them be on a tougher hull that more things can out-accelerate isn't going to save a Pathfinder if something is bothering trying really hard to kill it and has made it past our escorts.
If the Pathfinder is on a max-acceleration destroyer, it can just deny battle indefinitely without even needing to stay with the main fleet, because space is big and you can't fight in space unless both sides agree. On a frigate hull, the Pathfinder would have to stay with the rest of the fleet and resources would have to be dedicated to making sure it is protected.
Worst comes to worst, the ship stays on the edge of the system and jumps a few months of STL travel out and waits for the light from the fighting to show it is safe to return or if it needs to head for friendly space.
The thing is, if we go all in on speed it would be at the expense of defense. And banking on "Nothing will catch us" is not something that works all the time, since even the Eldar whose whole thing is being fast as fuck still get caught, and their ships are likely faster than we could hope.
Honestly, if we're fighting the Eldar any time soon, no matter what hull we put our Pathfinder design in, it's almost certainly going to die. Eldar Destroyers don't fuck around. We should be planning around things we both expect to fight regularly and are within our ballpark to handle.
Eldar ships 'get caught' because they are at ranges for combat. If an Eldar ship never wanted to fight, and thus never got close enough, nothing would be able to catch them, because in space, both sides have to agree to battle in order for battle to happen. A max Acceleration destroyer who starts trying to avoid battle from the moment it enters system, where it is 2-3 light hours away from the nearest enemy, could
never be caught by anything with equivalent or lower acceleration, and would massively draw out any chase with something with higher acceleration.
