I'm sure Westminster enjoys the taxes and duties paid by the Scots 
Personally, I think we are stronger as the UK, but fully understand their frustrations with decisions made in Westminster that only seem to benefit London people. I'm equally miffed with it...
I think you will find theres much much more £ flowing north than there is coming South.
Rightly or wrongly - Afaik taxpayers in London and an area of 50 or so miles around it subsidise the rest of the UK to a greater or lesser degree.
Personally,Im in favour of the union,on the condition that the Scottish/Welsh/N.I. parliaments are got rid off. At the moment. imo the pendulum has swung much to far in favour of the regions - prescriptions,uni fees etc.....
If we are to be a United Kingdom,we should all be governed by the mother of parliaments in Westminster, or call it a day and go our seperate ways with no alimony expected. Too much having cake and eating it presently imo.
Furthermore,very few decisions made in Westminster having an effect on Scotland, but Scottish MP,s sit at Westminster (as Prime minister until recently) and make decisions which apply in England,but not in Scotland - that is just plain wrong,unfair and completely undemocratic.