While the nebulae make hiding for both sides easier, this still gives us an advantage. After all, as long as the Hegemony does not even know we are her, they would not even try to sneak up on us, while we don’t have that problem. In that sense, the increased operational range of a larger nebula would be preferable, in my opinion.
Also, since the nebula does not contain any enemy stations, we could extend our sensor range via buoys to cover the whole edge of it. That would mean that we’d detect any aggressors before they even enter the nebula itself, thus negating any stealth advantage in the first place.