I purchased this BD-RE DL at the same time as a TDK BD-RE Dual Layer Blu Ray Disc. I then burned a different ISO image onto each disc, the one burned onto the TDK being slightly larger than the one on the Sony. Using the same computer, software and burner, the Sony BD-RE took almost three times longer to complete its burn. I suppose this could be some compatibility issue with my Pioneer Blu Ray burner, I don't know if that is the case. I do know I will be avoiding Sony BD-RE products from now on.