Incidentally, one of the key points of Guns, Germs, and Steel is that the vast majority of potentially useful flora and fauna are not easily tamed, bred, enslaved, or assimilated. Horses worked out wonderfully. Zebras? Not so much.I'm referring to the stuff that is accessible at a local level. Whether it's flora and fauna that could be tamed/bred/enslaved/assimilated or magical/fantastic effects with long lasting consequences.
Having half your workforce work at night is less than transformative. It just means that half of them work during the day and half at night, rather than all at the same time. This isn't useful unless you also have, say, an expensive factory that would go to waste without a night shift.As I said, infravision is a poster child here. The ability to have a workforce that works 24/7 has an enormous impact on every level of society.
If you're building roads, walls, aqueducts, etc., it doesn't boost productivity.
The key is whether these magical technologies are cheap and easy to use. Human labor costs roughly one silver penny per day.When you take all these things together, they don't add up to Feudal Europe in my mind.