I am going to have to agree with Two points which simonmoffit said, "Free from what" and the failures of Darien which brought the Acts of Union about.
I think it would be foolish to ignore that Scotland was a bankrupt nation due to Darien, and unfortuannaly weather you agree or not, going into union saved the rich of Scottish society (yet did not repay the poor, when they lost their savings in Darien - but what can you do when you had no political rights then?) Union did at least, serve Scotland well economically (Naturally it did not culturally). Now of course Scotland does not fair well in Union with England, my simple advice: Independence within Europe!
But I do strongly disagree with him when it come to who to subsiding who. N. Ireland receives a large subsidy from the Barnet Formula, Wales also does, But so does London, and officially Scotland does also. Yet how the "extra" £1,500 is sourced to the individual I would say that Scottish Oil makes up more than enough for it. (And if the Tory Government never Privatised BP, I am sure we would right now see a lot more than 12 or so billion on tax for N.Sea Oil yearly!)
But away from simonmoffit response and to your question:
I am at odds with what will happen when Westminster attempts to update Trident when the Scottish Parliament is against the idea - with only the Tory Party in favour of it - 17 members out of 129 to me doesn't seem like a majority. I was under the impression that Planning was a Devolved Matter, but then again Devolved Decisions can be override by Westminster if need be, and I really do not see the public up-in-arms about it if they did / do, as really we are not going to pick up weapons and fight, and I really do not see Scotland brining back 59 SNP MPs to Westminster nor opposition, not 59 Lib Dems.
To the Oil Argument - the SNP really hasn't said what will happen to the North Sea Oil, when Scotland becomes independent (as I do see that we will) will they nationalise the industry? the North main Oil "holes" have only a limited life, when Scotland becomes independent will they be mostly gone? What then? advancements in technology can only ensure the oil's life is continued, as much of our oil is hidden away and hard to get to.
Scotland has a limited voice in the EU, 7 MEPs give us one of the most limited voices a country of 5 million has. Independence, as described in the SNPs White paper would give us double. A voice in the UN, other than a British voce, which represents Westminster and therefore a majority of the English.
If you mean Free as in Independence, then it is doubtful that in Holyrood for this Parliament we will achieve the goal, However more Devolved Powers is, I would say a certainty. With the Tories in favour, the Labour Party in favour and well the Lib Dems have always been in favour of more powers. And I am sure the SNP will support any Bill for more powers, but the Parliament will, as it stands Reject any Bill for Full Independence. 50 MSPs simply do not cut it when it comes to passing a Bill. And even if it were, would 50% pluss actually vote for independence?