a) Saying a currency union 'would work' is not the same as saying that it carries no risks nor that it would work better than the system we presently have. The answer to these points is that it would and it wouldn't respectively, Rather it would be the least bad option because while it carries risks, these would be borne disproportionately by the rest of the UK and not Scotland. This is congenial to me because I live in Scotland.
b) If Scotland launched its own currency, it would undoubtedly see an increase in the cost of borrowing - to a degree that is unpredictable if the (admittedly extremely unlikely) event that King Eck carried out his lunatic threat to walk away on Scotland's share of the national debt. I don't like this idea because I have a mortgage and credit cards.
c) Currency union is the option post-Yes vote that looks the least like actual independence and I don't believe in independence. I'd put it more bluntly: if Scotland and the rest of the UK agreed a currency union, Scotland wouldn't really be independent.
This is me. Why others should favour it is more of a mystery. Two groups within the British Isles spring to mind:
1) Scottish Nationalists. At this moment in time their behaviour is tending to reinforce the impression I've always had; there's a fair chunk of the SNP high command that don't really believe in independence. How else can we explain their behaviour in the last few days? We should be clear about this: the 'threat' by George Osborne can only be considered a 'scare-tactic' to the extent that, not 'the peepul', but the nationalists are scared of what independence means. Currency union was the flagship of the 'independence by stealth' campaign. Vote independence and you'll hardly notice the difference. This has been holed below the water-line, hence the rage and the pathetic accusations of 'bullying'.