An answer by mrQQ here got me thinking about firmware progress regarding burn quality. I rescanned a disk I burnt in December last year @ 8x using 1653s/CS0C. Burn is perfectly acceptable and in fact is similar to burns I get now on latest firmware on both 1653s & 1673s. The only improvement (with new firmware) probably comes @ 12x and over speeds and new firmware in pipeline KS09 as demonstrated by OC-Freak seems to rectify Lite-on burning quality @ 16x (certainly with some media) see here for 16x burn using KS09.
I have included scan mentioned above - Ricohjpn R02 burned at 8x using 1653s/CSOC: