There's actually a huge amount of assertions you have made there are factually wrong.
I want to start by saying, by your request, we ignore the scientific basis and concentrate on 'benefits to society' I think is how you phrased it. I disagree completely with this principle. If something is safe, then there should be no reason to implement a ban.
Scottish farming is not GM free. GM feedstock has been in use for decades.
There has been a lot of misinformation online and in the media. You've hit on a few misconceptions, and many other anti-GM types in this thread have fallen into the same trap. There needs to be a public education programme that outlines a fair analysis of GM, which includes the benefits. At present the argument has been very one sided from a vocal minority such as Greenpeace and the Soil Association who have a vested interest in preventing GM introduction.
I agree that consumers should be allowed the last say in what they put in their body. Many consumers would welcome the benefits of nutritionally enhanced food. As it is, they are having the ban imposed on them, with no real justification. Why not give consumers the choice and let market forces decide? The gluten free etc sector seems to do very well out of this approach.
Maize that has been engineered for the cold shock gene would allow the crop to be grown in cooler climates. Why do you want to take the choice of crops away from farmers?
All crops remove nutrients from the soil, not just maize. You mention potato resistance. OK, one trait may be a negligible benefit. But what about stacked traits? Already 8 or 9 traits are being stacked in crop varieties.
By Scotland banning all GM crops it removes the ability of farmers to make the right economic decision for their farm
Do Scottish farmers consider Brazil and the US? Yes. Cash crops are commoditised crops. Farmers sell at futures prices that are heavily influenced by global stocks. You dismiss it as not an issue, and yet it is perhaps the most important issue of the discussion.
You say export markets should decide how we farm. Great idea. But you are supporting a ban on farmers being able to export GM crops to export markets. You are contradicting yourself. All the major agricultural economies have adopted GM (Canada, USA, Brazil, Argentina, China, Australia and India). All of these markets are potential major export markets for our farmers, but they are exporting with one hand tied behind their back because their counterparts are growing GM, and Scottish farmers are not. And soon English farmers will be growing GM crops, putting Scots farmers at a heavy disadvantage at home as well.