I've found that to be a general characteristic of Samsung drives, as they use the same chipsets that Liteons have used for a long time (Mediatek). As such, they often show the symptoms you mention--nice results scanning with Kprobe, but more accurate results when scanned with BenQ's.
The problems BenQ's report match my experiences with readability issues, so I don't rely on Kprobe results for those reasons. I know there are plenty of people out there who would like to argue with me on that point.
I switched simply because I like to own the current products mfg's are actively working on, and provide firmware feedback for them (as you can see by my active drive list in my sig). Once their updates seem to be waning, I figure they are considering it to be a mature design requiring minimal continued effort and then I pick up a newer model. These are my only motivations for upgrading drives--I do very little legitimate recording tasks other than Nero CD-Speed burns and analysis using my reference drives for posting in these forums.
Stability wise, the SH-W162C is probably a better choice as it is more mature and thus more well-tuned, whereas the SH-L162C doesn't appear to be up to the SH-W162C's standard yet so it is less of a "known good". At present most of my burns with x162L TS06 aren't up to the x162C TS11's burn quality standards in terms of PIF rates or jitter levels. Sure the burns are usable for the most part, but if you are using it for functional purposes (unlike me) the x162C would be the safer way to go in the drives' present states. The x162C definitely has far better media compatibility and burn quality than the TS-H552U ever did. Hopefully the x162L will eventually be in the same relative category vs the x162C, but it doesn't appear to be at present.