One big difference between the QA and the OL system is that the OL does not have a decocker. I saw a SW99OL in .40 S&W at the SHOT Show today and asked the S&W people about it and they just started to laugh.
Apparently one of the selling points they had been using on the SW99 line was the decocker. Of course, the absence of a decocker on the OL pistols now puts them in an awkward position.
It looks like the engineers and marketing people weren't talking to each other.