As someone who drives manual, and so actually having to downshift myself when necessary, I would rather negotiate a larger roundabout 100% of the time than having to stop at a red light 30% of the time.

On my current gearbox, I can dip to around 30 km/h and gently accelerate while staying in 4th gear, which I'd be in up to around 50 km/h. So if I hit an uncontended larger roundabout that takes me 50-30-50, I don't have to do anything, transmission-wise.

Manual driving culture is probably one reason roundabouts have been popular in Europe long before North America started to warm up to them.