I found two threads on MYCE (formerly CD Freaks) "Samsung SH-S223B" deals specifically with the differences between the SH-S223xs-->
http://tinyurl.com/ykh9ezt and a thread called "Samsung SH-S223 results & discussion"
http://tinyurl.com/yz9d7uu, with burn results, etc. There is a load to digest, but after a very quick look tonight, apparently the different letters refer to different countries of origin, and/or different chipsets.
I used to get excited about comparing different burners, checking out hacked firmware, etc. However, I think I have moved on. At this stage of the game, I think I'd just like my burners to do as they are told without me having to spend too much time in R&D mode. Perhaps I am becoming jaded.