I've done the 'have a go' bit myself but a long time ago when the criminal would shout 'OK, you've got me!' and then stop struggling. Now they are probably armed or at least not afraid of causing a great deal more harm then the incident warrents for their escape.
So, not sure I would now, certainly not for someone elses Rolexes as RT said, but if I was helping to protect life or my close community then I would probably still act if there were witnesses and not too many of them.