I havent really heard of any problems with Litie DVD drives, only good remarks for them up to now, but you know best in your case.
As far as choosing between the Pioneer and Samsung drives. I do have the Samsung 616F and i have mixed feelings about it. For instance it has a very bad audio extraction rate (max @ 12) which gives problems when encoding audio or extracting subs while backing up games that need it. Plus it aint supported from CCD (which i still use) so no FES etc there. I dont know if newer models are somehow improved though.
On the other hand it does its job as far as playing DVDs/reading CDs is concerned, i have used it now for 2 years without having a single problem.
I have also worked a lot with pioneers too, never had a problem with them too, plus i think they are faster when extracting audio.
So between these two, id probably go for the Pioneer. I would consider getting a toshiba dvd drive also.