Thanks for the reviews and comments on the Interphone F4. The information posted here along with the web bike review solidified my decision to buy the F4. After installation and a test ride I am extremely pleased with the unit. The clarity of the audio in reception or music playback is outstanding, and the digital processing for the microphone's noise cancellation is quite impressive. My Road King is pretty loud, and with my modular helmet's chin bar down the people I spoke with though I was on a land line. With the chin bar up and the microphone exposed to the wind (albeit behind a windscreen), the callers on the other end could hear some background exhaust noise only when I really jumped on it.
Can't say enough about the quality of posts here!!!