Bit of extensive googling and playing with keywords turned up this - I think this is in relation to Western Digital´s Raid Edition drives, but the logic should be applicable:
The YD model has TLER (time limited error recovery), which means in the event of a bad sector, the drive will only try to recover for 7 seconds before marking the sector bad. In RAID systems, this is desirable because for many RAID controllers, if the drive does not respond after 8 seconds, the controller assumes the drive is dead and drops the drive from the array (going into degraded mode). Thus "normal" drives have problems in hardware RAID setups when bad sectors occur. OTOH, TLER is not ideal in single drive (or RAID0) setups because in that situation, if you have a bad sector, you'll want the drive to do everything it can before giving up (which is usually on the order of 1-2 minutes).
Bottom line, for single drive and RAID0 setups, get the KS. For hardware RAID1, RAID5, RAID10, RAID50, etc... get the YD.
Hopefully useful for anyone else who has the same question, and to save some time googling.