Another problem with the HD in the HK radio is that the reception is awful.
The FM reception is pretty poor in comparison to my other cars. In our Jetta I could get DC101 all the way to Fredericksburg but in the Outback I only make it about halfway before it gets staticy.
The HD reception is even worse. Just driving around Northern VA (Fairfax, Reston, Centreville, Gainesville) the HD signal is constantly cutting in and out. When it cuts out the radio reverts to a standard FM signal and there is a slight volume change so it's fairly obvious. Of course if you are listening to a HD-only channel it cuts out completely. As a result I have just have the HD setting disabled.
The FM and HD reception are one of the very short list of things that bug me about my car.