As Bald Rick says, this is subject to law of small numbers at present as the fences are comparatively new, but yes as time goes by the statistical evidence becomes stronger.
On the GEML Brentwood, Harold Wood, Chadwell Heath, Goodmayes, Seven Kings, Manor Park, Forest Gate and Maryland have all had fences erected in the past couple of months. None of these stations have regular platform staff, although that may well change under Crossrail. Once the safety case certification is complete and the emergency gates are closed, we will be able to start measure the figures.