Maybe it's my game settings...

I tend to play on crowded maps.  On Serious difficulty I find that many of the "good" systems are already being colonized before I even get the chance to get the "free'" colonize a system in early game.  Paying the cost of early colonization is not possible because you won't have the strategic resources to pay for it.

Not sure if I agree that outpost attacks would make things unbalanced.  It's an ability that everyone gets.  I mean that if 2 empires are at war, why can't they destroy outposts.  You might want to do it because you want the area for yourself or to prevent them from expanding.

There is no adequate way of blockading an outpost to destroy it.  How many ships and at what rate?  Its a total guess and there is absolutely no feedback.  From what I've read in this forum and seen for myself in-game the outpost may have all the resources it needs to become a colony, irregardless of how many ships are part of the blockade.

Hey frodak, about your last statement, i dont think it is about How many ships. you have to count it like this: Scout ships, even at cold war, can blockade an enemy outpost and reduce its food/industry income (in case its a riftborn) but they do it very, very low. and if the AI you're playing whit activates at least one, or two buffs for its colony well... except that one scout ship might not be enough to destroy that colony. 

In order to counter that, you can build defender/attacker ships. And fill them whit movement modules so they get to the contest point faster. Then you will gradually destroy that outpost, and when it is complete, you can colonize it whit argosy again. 

Also, i have played a bit whit vaulters, and if you dont have the strategic resources for the faster colonization thingy, remember: you can buy them from the market. There is a specific tech that, if you research it, you will enter the market. you can get ab out 5 strategic resources for a very low amount of dust when you open the market the first time. 

And yes frodak, you can destroy other colonies as vaulters. You can invade them as vaulters and drop manpower on them, capture them... Or you can put defenders/attacker ships (or even tier 2 or tier 3 ships) in colonies to reduce their growth potential. The only concept i think it is unfair is to make ARGOSY  able to contest outposts. that would be unfair and buff the vaulters in a unnecessary way. :)

Hope this helps!

I updated my post because I used the word colony instead of outpost confusing the issue.

If a scout (or any ship) blockades an outpost it could start to starve the outpost.  Digging deeper into this, I've seen the indicator on the outpost go from 10 turns to colony to say 250 turns to colony.  That's not very useful and implies that the blockade is useless, you cannot starve the outpost by blockade.  Using ships that are better armed then a scout didn't change anything.  Why? Because it's a blockade not an bombardment of the outpost.  The turn to colony never became negative or indicated turns to starvation.

Declaring war doesn't matter either because it didn't allow the bombardment or invasion of the outpost.

I agree with what you say about the ARGOSY, but I would say that any ship with 0 attack probably shouldn't be able to blockade.  It's more or less a civillian ship.  I'm not asking for or suggesting any ship or empire to be different.

There are trade offs when playing as Vaulters.  Yes, you get buffs because you colonize instantly.  But in the games I've played I've seen empires get 2 or 3 colonies down before Vaulters get the 1st free colonization.  I don't have an issue with that its part of the balance of these things.

I just don't see why outposts are so special that they are off limits to attack and invasion.