It is my hope that Scotland votes to keep Britain together next week, partly for emotional reasons- I'm half Scottish and much of my family is from there and I feel a sense of nationhood that doesn't stop at Berwick. It also seems to me that Britain is a stronger and more formidable country than merely England, Wales and Northern Ireland.
Having said that I do think the 'No' campaign are wrong to concede nationalist demands on control of the welfare system in North Britain. Single currency areas like the UK require transfer payments from rich to poor areas in order to compensate for poor areas being unable to devalue their currency to compete. One of the quickest ways that an economically hard hit region to receive transfer payments is through the welfare system.
Paul Krugman (who despite his hyper partisanship is a renowned economist) explains the process with a comparison of how Spain and Florida were affected by the global recession here. Essentially when Florida's economy crashed, it automatically received more money from Washington whereas Spain did not automatically receive extra cash from Brussels leading to a much weaker fiscal position- because despite currency union Germany isn't willing to fund Spain's welfare system.
If Scotland manages it's own welfare system some of the automatic stabilisers won't work in the case of a shock to Scotland's economy.
More devolution is inevitable but welfare should remain substantially a UK wide issue.