Originally Posted by dfmz
The Garmin Zumo 660 is probably the best rpoduct out there (the 665 is the same product with satellite radio).Make sure you buy a traffic receiver with it. It's worth the 50 or so bucks, especially if you live/drive in a an area with heavy trafic.
The Interphone F4 is a great product. To be honest, wasn't aware it was sold in the US! The Cardo G4 is a viable alternative.
I bought a used GTM-12 antenna from eBay for my Zumo 660 and paid ($60?) for the lifetime traffic subscription that goes with it. The traffic subscription is provided by ClearChannel, and is transmitted from their FM radio stations.
(If you have a Zumo 550 or Zumo 665, you can also pay a monthly subscription for XM, which offers a traffic option.)
My experience with the GTM-12 and ClearChannel traffic has been marginal at best. I live in Southern California and good reliable traffic info would be helpful. Most of the time I am in heavy traffic, it doesn't show up on the screen. If you want to see a traffic speed map (red, yellow, green) the Zumo hides a lot of other useful details. The traffic feature seems to be based more on incidents, rather than actual traffic speeds. There was one time where an accident closed the freeway ahead of me, and it reported the problem - first as a delay, and eventually as a closure.
One good thing - I have been on several very long distance rides, including one across the country, and found that it picks up a traffic signal in most urban and even some fairly remote areas.