I had to chuckle at the reference to superbike braking on the new Multi. No mention of the rear brake though.
Are basing that on a 2012 or earlier bike? I have one of the 2012 bikes with a rear brake that just about works (but it's not great). Today the dealer gave me a 2014 MTS as a loaner while my service was being done. The rear brake was much much much improved so there has been an improvement to the rear brake on the 2013 or 2014 bikes.
Mine worked great, then went off, annual servcie, worked great again. Suggest delaer may have bled the system.