I have the Sony modified by Radio X Tuners. The mods improve the sound quite a bit. I also use the FM Reflect with it. HD allows me to receive our classical station on my downstairs system. This station recently moved to a lower power transmitter and reception has suffered.HD (carried on 89.7 WGBH HD-2 Boston) is quiet and fine for background/non-critical listening. Fortunately,reception of the FM signal (99.5 WCRB Boston) is good in my upstairs listening room with a Marantz 10B using a Direct Reflect.
I have a Polk i-Sonic in the bedroom with HD, that is essentially used as an alarm clock. The sound is good. Ive connected a small PSB sub which helps it a lot. Interestingly, the Direcr Reflect does not work as well on this side of the house. I have a Magnum Dynalab whip that does a better job with the Polk in this location.
Bottom line is that Sony should add an optical output, antennas are critical, and HD is good but does not replace analog for critical listening.