AS far as HD, I've read a few things that may or may not be true, so take them with a grain of salt, and maybe a shot of tequila to go with it. Supposedly, HD is being driven by Clear Channel, and the receiver is saddled with a $50 licensing fee when manufactured. Consequently, the quality of a receiver wth integrated HDRadio would likely be a lot lower than others at the same price point. As HDRadio isn't broadcast at the precise same time as FM, (a few seconds delay,which is significant,) switching to FM when the HD is lost and back when it is regained would be REAL annoying to me, but may be acceptable to some others. Again, take that with a grain of salt or two, and something to rinse it down with while you verify it or find out it is wrong.
The JVC models that I have considered in the past didn't have separate power antenna controls and amp power controls, so if the unit was powered up, the antenna was extended, even if a CD or other non-radio source was selected. If you have a power antenna, this may be an issue with a JVC - I haven't looked at the installation manual for that particular model to be sure.
Hope this helps.