Yeah, the phase missile block on culture (I assume its only in culture) is a great boost to the Advent. I still don't know if I'd rush to get it, but if you're in a long game with the Vasari certainly the late culture techs are worth getting now, which naturally make it easier to get.

That said, for the loyalists the impact of the deliverance engine might be mitigated by the fact that all of their planets can produce culture and their titan can apparently instantly capture planets. Which means they will be fighting in gravity wells with their own culture in it most of the time anyways.

Well-placed Novaliths seriously screw everyone over, but they don't do anything to a Starbase-protected planet...

The Deliverance Engine was always just rather useless, as the culture it produced never lasted long enough to remove more than like 3% Allegiance from an enemy planet, or just annoy people who were struggling to recolonize...

it could bolster your fleet a little with the passive culture boost, but other wise, it was better to invest in different things...

The Kostura Cannon, however, could open a phase gate to a distant homeworld, as well as disable any repair platforms or non-starbase defenses, allowing your fleets to attack enemy planets with ease...

If these remained relatively the same for Rebellion, the Kostura cannon's usefulness has just increased a hundredfold, as the new victory conditions allow for you to assassinate their flagship or their homeworld without having to fight through to those targets with your fleet. I think that the Rebellion Vasari are going to be obnoxiously strong.