Many thanks again, Graham! I'm aware that religion certainly wasn't as much an issue with the Scots as with the Irish and loyalties were more divided, nevertheless the question remains. I know of a number of prominent Scottish emigres or their descendants (first and foremost of course Berwick or Étienne Macdonald, Marshall of France or Barclay de Tolly), but it seems emigration was limited to some nobles rather than whole thousands of soldiers and serving in foreign armies was - at least for nobles - not uncommon in that period (viz. Prince Eugene and others).
Then, I came upon a strange "order of battle" for Sheriffmuir
and the names of the units listed there sound at least in part very Dutch (Welderen, Zoutland etc.). I know there were Dutch troops at the Boyne, so perhaps ...? Or they got it wrong on their website, who knows?
The name on that is wrong. The document clearly says "In Scotland" not "At Sheriffmuir". Dutch, and if memory serves, Swiss, troops were recruited by the British Government as the British Army had been massively downsized when involvement in the War of Spanish Succession ceased. The giveaway, as well, is that it lists Cadogan, who didn't got to Scotland until after the battle.
As for Scots/Irish mercenaries overseas as opposed to Scots aristocrats and descendants, the situation was very different. The Jacobite Risings were about a split in the ruling classes. If you lost out, then you fled to France (if you were a Catholic) or to the Netherlands (if you were a Protestant), a fine tradition going back to the start of the Reformation.