If you have firmware 1.01 then they should burn at 2x, but if you upgraded to 1.21 then they will only burn at 1x (that happend to me too). It seems that Pioneer is screwing their own customers by "black-listing" certain kinds of media. Expect a hack with in a month, there are people already working on a hack. Check out this forum:
http://forum.firmware-flash.com/viewforum.php?f=2