I realy like the way, jumpships work in aurora.
Yes, jumpengines take a lot of space, but look at the steam plants of WW2 battleships and carriers . Those took a lot of space too (more than the regular engines of spaceships in aurora, I think). I don´t know about moders naval vessels, but I doubt less than 20% of total mass are sufficient.
The thing is: With jump engines so small, you can mount them on a warship and still arm and armor it propperly, it becomes a no brainer to mount them on all military ships, simply because the trad off (IMO) is negligible.
As it is now, there are so many choices.
Do I form a taskforce with just one or two jumpships, that will have to shuttle back and forth to bring the whole force through a jumppoint (and risk defeat in detail in the process), or am I including enough jumpships to bring the TF through in one go?
Darn, if only I could fit in this quad PD-turret, but this would bring the mass of the CE above my current jumpengine limit, perhaps if I reduce armor or shields
Do I go the way of jumpgates, freeing up my design process considerably, but also open my system to possible aliens, or do I go with jumpships, limiting my desing possiblilities to a rather resticted tonnage?
What if the jumpships are destroyed, stranding my whole taskforce out in nowhere? Hm, I will have to build the JS to withstand an attack, so, do I armor/shield it or give it active defenses, as there rarely seems enough space to do both?
Decisions,decisions, decisions, that´s what I like!