The main difference with the classic style Unger BOAB is the fact you can only use it on the right side of your body, where as the new style BOAB you can use on both sides.
Yes it has been mentioned on many occassions that rubbers are being nicked, I have found that there are less complaints of this with the new style, although the blade protector that Soapnational sells is a great idea and I have recomended this to end users several times.
At the end of the day though BOAB are a very individual choice, we find that both styles sell just as well which is why both syles are still available and the old style hasn't been discontinued.