I teach economics at a university so I apologise if this seems like me trying to lecture people. I actually see costs and benefits in both a Yes and a No vote even though I have weighed it up and think No is better for the country and my family.
The real problem with this argument is that the economy is more complicated than just a debate about whether Scotland subsidises or is subsidised by the rest of the UK. It's not as though we have a certain amount of money and chopping the country in two will simply give one bit more money than they have now. The real point in the UK is that it's supposed to be in everyone's interest and that's largely true in my opinion whether one bit pays more than it receives in spending. Getting rid of it will likely make us both a bit worse off at least in the short-term.
The subsidy question is quite difficult to answer but using the Scottish government's figures we can make a good stab at it. Basically, in the days before we had hit peak oil production, it would have probably been correct to say the oil (which is mostly - over 90% - in Scotland's territory) would have "subsidised" the rest of the UK. However today and in the future this is a somewhat different picture. Last year, for instance, the Scottish government's figures (with oil included) showed Scotland generated around 9.1% of UK taxation revenue but received around 9.3% of UK spending. So it was getting more in spending than it put in during that one year. In previous years however the trend was usually the opposite.
We can expect this from now on to hover around where it is now for perhaps another 15 or so years - with perhaps in some years Scotland generating more than it receives and in other years generating less. After this the oil production is projected to decline quite sharply after 2030 (so about 14 years after independence) at which point unless there is another discovery of oil, Scotland would be generating quite a lot less UK taxation revenue than it currently receives in spending. If you look at the last 10 years or so Scotland has consistently generated about 8.3% of UK taxation revenue (without oil) and received around 9.3% of UK spending. So after 2030 that situation would be a very good deal for Scotland.
This is what the politicians don't tell you. The No side doesn't want to admit that in the past Scotland generated more than it received in spending, but the Yes side doesn't want to tell you that in the future, when oil declines, the figures don't really add up. As we can't rerun the 1980s/1990s as an independent country that leads me to vote No.
There would be some short-term problems (the currency, the market reaction, businesses relocating from uncertainty and so on) that I think we would get over eventually, but by then when the oil declines (and we only have about 14 years until the point it starts falling quickly) it really is hard to see it making us better off than we are now. I think we can get most of the benefits without the risks just by voting No - I know some people don't trust Westminster (I'm one of them) but I think really looking at the figures it's the best option for me.