I'm a little skeptical that it would be safer for pedestrians and bikes. Bikes need to merge with traffic already in the roundabout instead of simply going straight through an intersection, and pedestrians would need to always check for oncoming cars rather than being able to mostly rely on lights telling them when they can cross.

But then most of my experience with roundabouts is with large, multilane roundabouts so the traffic is still pretty fast - maybe smaller roundabouts with significantly slower traffic would be safer than I'm picturing.