Seems like Lite-On do start to improve!
Playing with a pretty fresh (dated April 12th) 1693 firmware on my 1673S - noticeable improvements I have to say.
TYG03 @ 16x. Write time: 6:10 Unfortunately the discs I have came in a very damaged package (Thanks To Miflop Media in Spain for sending it my way) and thus many discs have dust particles or minor scratches. So the PIE sikes and PIF spikes at the end is due to disc defects…
MCC03RG20 @ 16x, Write time: 6:10.