So, if there is any chance of this thread gaining some dignity as a balance topic, I'd suggest focusing first on whether Vasari SBs are OP and need changes. If they are, then what the changes could be would be step 2. I do not think anything productive will happen, but I could be surprised.
There is a lot of asyncronous balance stuff in this game. Advent get culture at 2 labs and trade at 3. TEC are vice-versa. That's an easy asyncronous balance where you can't really cry OP one way or the other, although you could argue trade is a better deal than culture. But then you've got to factor in everything else - ship quality of the factions for example.
So, you can't just look at the Vasari SB in a bubble - it has to be in context. If you nerf it too hard or buff the other SBs too much, then you're overlooking the fact that the SB superiority could've been masking other deficiencies. Nerfing Wail and the Eradica too much without making any improvements to AR elsewhere is another example.
A basic question is "Can it reasonably be countered in time and for a reasonable cost?
Sareth feels TEC don't have much issue doing this (LRMs, Ogrovs, bombers later on). Advent do have a much harder time as their only options are early bombers or to have mass disciples ready while it's still building. So if it's only Advent that have a potential issue, then you have to question the logic of changing all SBs. The work, the complexity, the opening of other potential balance problems just doesn't make it a logical choice. Either buffing Advent's ability to fight off SBs or mild nerfs to the Vasari SB make much more sense, even if all mobile SBs could be "fun to try out". Let's be realistic. Otherwise this is no longer a balance topic, but just a "wouldnt it be cool if this was in the game" topic.
Generally, balance topics where you actually want the devs to notice and make a change should be ones that they can feasibly do first of all. If they are listening, they probably want to see some kind of consensus amongst players that many are finding this to be an issue. Solid reasons why help as well - either via replays or in game stats. Maybe something is just too effective for what it costs, comes out far too early and can't be countered, etc. Titans in the beta were a good example of this. STTC in its original form was a good example of this. You had replays, stats, and lots of supporting feedback and consensus amongst players. All of this is completely absent so far in this thread.
My experience in fighting off Vasari SB rushes is that as Advent, you need bombers and disciples as much as you can afford and to have scouted him coming at least 2 jumps away. As I've said before, it's a strong tactic but it can be beaten if you are prepared. I don't like it because strategically it makes that game's matchup all or nothing - SBs are expensive and if you kill one off and force a retreat you can usually roll over him. The whole game often comes down to that SB battle, especially if it's an early rush he's invested all in. I would hate to see the strategic focus of the game become this one dimensional for all races.
Personally, my wish would be that all SBs can only be built in owned gravity wells. This way, they would purely function as defense and the advantage the Vasari one has would be contained to its own wells. They would have to rely on their ships alone to advance but would have a more flexible SB for defense to fall back on. This would take the cheese factor out of using Vasari SB as well - oh shit, wasn't looking and he SB'ed my HW while I was microing this other battle, etc.