My own view on these targets has changed in recent years.
Having seen pellets rebounding off them and been hit by fragments as well my view, in the light of the ever present 'health and safety' culture is that they are a potential hazard and steps should be taken to alleviate risk.
Sorry if this sounds frightfully 'lily-livered' but the simple fact is I don't relish being the one with my nuts on the block if there is an accident involving a target such as this.
IMO we should consider going to 12 yards as a minimum distance, as that little extra distance seems to cut down on rebounds coming back to the firing point.
For indoor target shooting using low power rifles, I don't see any need to change.