For beam defense, the difference is how fast a ship can kill another at point blank, 10,000km range vs how fast it can do so at whatever the jump distance a squadron can get from the jump point, plus how far they can go in 5 seconds.
There is also an effect on design, as a ship designed anticipating that the enemy will have to cross within 10,000 to achieve its objective is a bit different from one expecting its first and possibly only fire will be at 100,000km.
I haven't done the math, but I suspect a beam ship can kill an equal sized ship in 5 seconds at 10,000 km, possibly more than one, but it might take as much as a minute at 100,000km.
A ship designed to pursue an enemy after transit in order to stay in range has a lot more space devoted to engines than a ship that only has to be able to transit in and out of a jump point with a squadron.
Huh, I'd forgotten until now, but I've actually done
something like this. While engaging on the far side of the jump point was essential, it only made victory "barely possible" - nowhere near "easy". The big problem is that they can jump the instant they reach the JP, so you never get that ideal point-blank shot at them. Thus if they have sufficiently extreme speed compared to your engagement range, your options are extremely limited (and if the target had been shooting back, I'd really have been in a pickle).
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