There was some discussion about them on lawnsite (forum for lawncare, landscapers, and about everyone else). It was maybe a year or so back? The new commercial LB was a very short lived model. I'd imigine the reason being is that LB isn't really sold at "dealers" anymore, only box stores, so not many dealers really had a place for them. I really don't see many similarities between any of the professional and commercial Toro units and the LB. The commercial LB looks a lot more like the one sold at home depot but with a better motor and those fancy wheels.
I too was hoping that the commercial LB was going to be a "new" M-series, unfortunately not, though Toro has a model now that appears to have the same deck, just came out a couple years ago.