If I was living in Scotland, then yes, I probably would opt for winter tyres as well.
I see you mentioned that all seasons are a compromise between summers and winters. The real question is, would this compromise make much of a difference in everyday driving or only on the limit of the vehicle?
Additionally, there are some tyres - like the Michelin Cross-Climates which seem to have no compromise whatsoever, bar the price of course but then its still cheaper than getting an extra set of tyres.