It is interesting to me how much traction this is getting considering just how loyal Scotland has historically been to England. Scotland has always contributed disproportionate troops in British wars, including the American Revolution.
As well as the factors already stated: at the time of the American Revolution, being in the British Army was the only way of legally wearing the traditional Highland dress.
Scottish banknotes don't tend to be recognised in English shops, BTW.
Depends where you are. Places in England where lots of Scots go, like Carlisle or Blackpool, don't have a problem with Scottish notes. You can get away with them at most places in Greater Manchester. London and the south, on the other hand, doesn't like Scottish notes at all.
(Back in the mists of time, one reason why the twelve-sided brass 3d coin was introduced is that southerners didn't like the tiny silver 3d, although it was popular in Scotland.)