Let me be *more* pedantic. Mechanical trail isn't a bicycle thing. It is a physical property that has a basic effect on practically every steered vehicle in the world. It is so well understood in terms of stability that entire motorcycle companies are built around it. Heck, Mazda toyed with the suspension system of their 2015 Mazda 3 specifically to add more mechanical trail: they have entire engineering videos about it. Whole caster systems rely on it in industry. The effect of mechanical trail on bike and motorcycle steering stability is exceptionally well understood regardless of what you may have read on the "internet".

I think it's very well established that low trail bikes are much more challenging to control at high speeds except in straight lines and gradual curves. And that *definitely* goes for the Moulton.

But yes, gyroscopic forces have been proven to have essentially no effect in a bike.