I just purchased a USA-SPEC PA12-BMW yesterday (found a place here in Phoenix that sells them for $100 out the door). I replaced my DICE with this, and I have to say the sound quality is night and day. The USA-SPEC has no sound quality issues at all, no buzzing, no tics, wider sound spectrum, and isn't that really the most important thing about a music device? I am really liking the sound!
I do have one minor issue with it, and that has to do with text display when it is on AUX. I like having the iPod displaying the text, but I don't see any reason to continually display P 06-01 and AUX the whole time the AUX channel is selected. It would have been better to display AUX to show that you are on it, and the let the clock display, that is something the DICE did, that I liked.
I had to change my OEM Sirus to my plug and play, since my Sirius internet access ran out on my account, and I need to listen to Stern at work :-) So, I will be using the AUX about as much as the iPod, and if it isn't displaying song titles, then it should display nothing and allow the clock to display. Other than that, I am really glad I made the switch, so far so good. Assuming I won't have to a battery reset every month or two, I will stay a happy customer.