Liteon DVD burners are great for +R writing. Don't expect anything for -R writing. I had a 411s, 851s and 832s. They were solid for +R and sucked for -R. Since I have players that only use -R, Liteon was no good for me.
I bought a NEC 3500a in the fall. I loved it so much that I got a NEC 3520a around Thanksgiving and just last week got another NEC 3520a.
I will only use Liteon's for EFM encoding.