You can still get 8x and 12x drives brand new if you look hard enough.
Having said that, a modern writer does write modern discs better, for two reasons...
1) Modern media is optimised for >=16x burns typically,
2) Modern writers, because they have to write so much more quickly and remain accurate, typically write with extremely high quality at 16x which is well within the capabilities of the drive.
I can *guarantee* that a good quality, modern writer will write better at 16x than an old writer (even one which has never been used) will write at 1x or 2x. Especially with modern media, which the old drive will not be optimised for and will therefore make a "best guess" about, quite possibly a less-than-ideal one.
The only thing you need to be careful of is writing in Z-CLV or CAV/P-CAV mode. This can and does affect writing quality. Write with the fastest speed a modern drive will allow when burning in CLV mode (typically 16x or 24x for some new writers).