I think shrouds are probably safer. For saw-stop to work the blades would need to be quite heavy duty (vs. the thinner blades that are common now - those would

I think shrouds are probably safer. For saw-stop to work the blades would need to be quite heavy duty (vs. the thinner blades that are common now - those would simply snap off if you tried to stop them in a hurry!), and heavy duty means more load on the motors, lower response time etc. Additionally, if you're going to allow the blades to hit anything you more or less need to accept that it will result in a crash, even if you stop them immediately. Better to just guard them from contact in the first place.