NEC's is a hack.
Pioneer will most likely NEVER be flashable to DL.
DL upgradabilty list: http://forum.rpc1.org/viewtopic.php?t=25780
Though if I were you, I really wouldn't care that much about DL...
1/ DL media won't be available for over another month
2/ DL media will be very expensive compared to SL
3/ DL media will burn veeeeeeery slowly
4/ DL media reliability/compatibility is worse and is quite questionable
5/ DL is really a big hype right now... the only reason why people are even playing with DL upgrades is because it's the "hip" new thing to do and it give 'em bragging rights, but I reckon that when DL media comes out, most people with DL drives won't actually be burning and DL media
6/ Of course, if you *like* to tinker with experimental technology like DL, then that's different ;)