The factory centre locks developed a reputation for seizing onto the hubs (mainly I suspect on cars where the wheels were not frequently removed)
There was talk of electrolytic corrosion between the wheel and the hub and that the securing nuts were distorting with over-torquing. Not sure really what the root cause was, but they did become unpopular , possibly as a result of these tales.
They do have one big advantage , in that they are 16 inch diameter , so you get a much larger choice of performance tyres than is available for 15s.
Like Richard I prefer alloy wheels , after 32 years of wires on my +4 I was getting fed up of the constant battle to keep them looking reasonable, I didn't go down the centre lock route at the time, but perhaps wished I had in retrospect.
