I was at NAB Philly checking out the IBOC Stuff. Most of the aftermarket car radios were less than impressive to me. The best one that I used was the Dodge Factory radio. That by far had the nicest sound on both the analog and the digital, and handled the transition from the analog audio to the digital audio with the most finesse. It was also the most sensitive and quickest to get a lock on the HD signal. Unfortunately it will not be available in the cars until the 2008 model year. The other drawback is that it is not multistream capable. In fact I didn't see that any of the aftermarket car radios were.
If you cant afford a whole new car stereo, there are also going to be available little modules about the size of a cell phone that will receive HD, and they plug into non IBOC car radios where you would normally plug in a CD changer. These units were also pricy at around $399 to $439.
As far as tabletop, the Boston Acoustic radio was a little more impressive than the Radiosophy model. Both of these tabletop units are nice and portable, and both receive the multicast stream. The Radio Sophy has a docking station with speakers in it. The funny thing is that it sounded better when they pulled it out of the dock and pluged a set of computer speakers into it. Not that the audio from the Boston Acoustics speakers was any better than the Radiosophy dock, but I liked that it took up a lot less room than the clunky Radiosophy Dock.
Unfortunalely I didn't have a chance to check out the Yamaha Tuner.
A few notes about HD. I was suprised that the FM didn't really sound much better than the AM. I thought there would have been a lot more bandwidth to play with on the FM for better sound quality.
Also, many of the radios were sensitive enough to pick up WOR Analog from New York City pretty clearly, even though we were in Philadelphia. They were also able to indicate that WOR was putting out an HD signal. None of the radios were able to get a lock on the digital signal from WOR. Incidentally, The radios also picked up the analog signals of the non HD stations WFAN, WCBS, WABC all pretty clearly. Also WTOP from Washington DC.