After sometime, here is a brief supported media list:

DVD-R

TraxData 8x-R RITEKG05 ->12X

CMC Magnetics 8X-R CMC MAG. AE1 ->12X

Verbatm 8X-R MCC 02RG20 ->12X

TY 8X-R TYG02 ->12X

Maxell 8X -R -> 16X

DVD+R

Philips 8X+R PHILIPS C08 ->8X

Optodisc 8X+R OPTODISCOR8 ->8X

Maxell 8X+R MAXELL 002 ->12X

TY 8X+R YUDEN000T02 ->16X

Intenso 8X +R PRODISC R03 -> 8X

TraxData 8X +R RITEK R03->12X

CMC Magnetics 8X+R CMC MAG E01->16X

BenQ 8X+R DAXON AZ2 ->8X

TY 8X+R YUDEN000T02 ->16X

Verbatim 8X+R MCC003 ->12X

MKM 8X+R (new type) MCC003 ->12X

Ricoh 8X+R RICOHJPNR02->12X

Note that the above speeds taken from DVDInfoPro without any burning tests...Its rather dissapointing also that some 8X/16X +R rated media supported only at 4X, it seems that ASUS needs work at the firmware