Wings over Scotland is an interesting site. Its comments on the issues I know a bit about is that some of what it says is correct, some if it is arguable (albeit couched in terms of propaganda) and some of it isn't.
Its comment that Scotland as a newly-created state would be free of any debt is correct. The basis of this is that states, like people, aren't generally born owning property or obligations. Arrangements have to be made if this is to happen.
What it doesn't say are two things. Firstly, how walking away from the UK without debt would result in an AAA credit rating (thus meaning less borrowing costs for government). They have no evidence that it would, because I don't think any economists think this is really likely to happen.
The second point it doesn't mention is that independence is in the gift of the Westminster parliament. I have noticed some Yessers assuming that the referendum is binding on Westminster under the Scotland Act. However, it isn't. Westminster could refuse to legislate until iScotland agreed to take on its fair share of debt.
The third point it doesn't mention is that the rUK can unilaterally veto Scottish accession to the EU. I notice that WOS takes a bob each way on this issue, saying that it is arguable that Scottish secession would mean the disssolution of the UK and thus separate applications by iScotland and rUK. But if this is correct (and it isn't even reasonably arguable, btw), assets and liabilities would be proportionately split, and iScotland would not be able to walk away debt free.
I think points 2 and 3 are quite extreme measures. But so is refusing to take one's fair share of the debt. I really do fail to see the moral case for saying that the rUK should enter into a currency union with Scotland against its interests. I actually fail to see how what rUK decided would be any of iScotland's business.
As an interesting aside, when Ireland seceded from the UK, it didn't take a proportionate share of debt. I've never read an explanation as to why this was. Ireland became de facto independent, then the southern counties took Dominion status in 1922 (therefore back under the British crown), and then became fully independent in 1936. It's possible that no one actually thought about it. The UK eventually gave up its demands, but that was after blocking Irish membership of the LON and UN for some period. There is probably a backstory, but I've no idea what it is.