Edit: I added an idea of how I'd like the issue fixed at the bottom of this post. It's basically the same thing I posted in one of the posts below, but I suspect nobody in IC/SD has time to reap through these walls of letters, so I copy-pasted th idea here for easier reference.

This is a hard one to fix. Every other matchup is more or less fine, maybe requiring some minor balancing (nerf dmg of that thing, buff hps of the other, etc.).

However, there is a serious problem when you're a Vasari assaulting another Vasari player, who got 'entrenched' (as in - has a deployed starbase with 2-offence, 3-defense +some other upgrades).

You see, when a Tec/Advent player assaults another player, they can use the specialised torpedo cruisers against the defender. On the other hand, the defender has no use of these units. So this is a tactical difference that can be exploited.
Please note that torpedo cruisers have a superior range to that of a starbase, which means that the defending fleet has to move out of their starbase's shadow a little to defend it. If the starbase is orkulus, it will float in and engage the cruisers. Still, if you pay the same amount of money on torpedo cruisers as the defender paid for the starbase (with upgrades), that fleet will easily wipe the starbase. So it's a low tech-level hard counter there.

Also, when a Vasari player assaults another faction's gravity well, they can construct their offensive starbase out of the defending one's reach. Two options are available for the defender:
- move out and kill the starbase hatchling. This is very similiar to defending against torpedo cruisers, only the defender doesn't really have to do anything, because an unbuilt starbase doesn't pose a threat yet.
- wait for their SB to get built while preparing defenses. You have to understand that building a fresh 3k HP, 149dmg Pulse cannon naked starbase is by no means a game won for the Vasari. They still have to take out the enemy starbase and the defenders can bring torpedo cruisers to eliminate the threat. So this is no easy win for the vasari, but more of an all-or-nothing gamble.

The only screwed up match is Vasari vs Vasari. Simple reason - everything that works for the assaulting team also works for the defenders, but:
- the defenders can have minefields ready
- the defenders can have a beefed up starbase ready that will mow down the one being built by attackers
- the defenders have tactical structures set up
- the defender's (upgraded) starbase moves and the attacker has to set up its own in the same gravwell.
The last point is what makes Orkulus viable against Tec or Advent starbases, but it kills the offensive capability of it against an already deployed Orkulus. Why? Because the attacker's starbase will still be under construction when the well-developed defender's one drives by and starts tearing it apart.

All of this means the assaulting Vasari have absolutely no trick thy can use against the defenders that the defenders can't use against them. An assaulting TEC/Adv can use torpedo cruisers against any defenders without fear of having these used against him. A Vasari assaulting Tec/Advent can build his orkulus out of the enemy SB's reach. Nothing like that works in Vas vs. Vas match.

Some say Kostura is the attacker's advantage, but it's way too far in the tech tree and way too expensive to be viable here. Reason: everything one needs to down a starbase in any matchup except Vasari vs Vasari (torpedo cruisers, Orkulus) is limited to tech-level-4 bracket, while Kostura is tech-8. That and lots of other reasons mentioned in the spam below make the Kostura more of an end-game trick than a counter to a deployed starbase.

Hard one to fix... any ideas?

EDIT : my idea of fixing the issue. Please note that I DO NOT want a torpedo cruiser for Vasari.
Balance doesn't require everyone to have exactly the same tools.

Protective Nanites - research, tech level 3-4 in fortification tree.
"Jarun Migrator is equipped with a payload of special nanites which temporarily shield the Orkulus Starbase from heavy defensive fire when deployed in fortified enemy systems."
Requires: enemy Starbase in orbit (built or in construction).
Duration: Construction period and up to 120 seconds afterwards, if a hostile Starbase is present.
Effects:
- max Shield Mitigation increased by 5%
- Shield regeneration 10 sp/sec
- Enemy Structure damage reduced 100% (game mechanic wise; that would result in 50% actual reduction applied to damage coming from defender's structures)
My reasoning - such an upgrade would be of little use against TEC or Advent, because the shield mitigation bonus and regeneration are minor, plus you are going to deploy your orkulus out of their SB's reach anyway. The damage reduction would help the starbase survive against a defender's starbase early, but the Protective Nanites would fade off before you are able to develop the Orkulus enough to cause any serious damage to the defender's Starbase. Without at least level 2 attack and level 1 defense, an orkulus cannot scratch a half-developed argonev (try for yourselves, a lvl6 Vulkoras does better!). So this damage reduction would actually be effective only against Vasari, because wherever you start building your Assaulting Orkulus, the defending one is gonna start pounding on it just a few seconds later. 

This is just an IDEA of the type of tweak I'd like to see. Something that doesn't say "Boosts orkulus offensive capability against another vasari" (cause that would be retarded in a number of ways), but something that would sound sensible in general, yet truly shine against a defending orkulus in particular. And no torpedo cruisers for Vasari please.