Odd, I had the ebay cheapies, the crank side worked flawlessly, the other side bent, buckled and rippped the threads out of the crank before it unscrewed but left the crank on the taper.
So, I am not really sure about them,but then I have observed the more expensive ones from bitd had a captive washer on them to I guess bear on the inside of the crank square. As to whether this helps, I don't know, but I guess greasing the things might have stopped the one I had ripping out, as sea wind and rain kind of irritates aluminium especially where it is in close contact with steel and moisture.
But they are nice for pimping your ride when colour coded to your paint scheme.