NEC Europe announced during April the newer 3540A writer, with more enhancements, if you have the time to wait...
DVD +R: 16x max.
DVD-R: 16x max.
DVD+RW: 8x max.
DVD-RW: 6x max.
DVD+R9: 8x max.
DVD-R DL: 4x
CD-R: 48x max.
CD-RW: 32x max.
http://www.de.nec.de/productdetail.php/id/1240/lang/ENG
if the price is no problem, the more expensive Plextor 716 is an option, but they got last week in two days correction F/W updates, so all the latest machines are not yet ready, or 100% completely proof with the latest faster media!
It's difficult to predict,
I went for the 3500 to the shop, and got me a newer 3520A wich F/W should released in the month March, for the waiting of the official DVD-R4 speed standard, and now its April and now this F/W is promised on 1st of May, so all the competitors need time, and to completed hopefully the F/W with the latest bugs elimimated and the PI/PIE testing, and quality scanning possability altogether in one time!
succes, Harry