Pureboy

I'm also a 660 owner, and yes, if in the Navigation options you select "avoid traffic," it will do so. I've used it in AZ, CA, and now PA, NJ and NY, and I have mixed reports. If you are mainly travelling within a city, or a commute of an hour or less, it can be a godsend. It picks up slow traffic, accidents, and road construction. However, the accuracy depends on location. AZ (Phoenix) info was very good, if not perfectly accurate (accidents reported that have already been cleared, slow traffic no longer so slow, etc.). I didn't encounter traffic in CA. But I've been heading out from PA (near philly) to NYC/NJ for the last 5 or so weekends, and sometimes the avoid traffic setting is just a bit too... skittish. In what is normally a 1.5-2 hour trip, it sent me through highways instead of faster freeway/turnpikes. While much more scenic, I doubted if it really made up time. Sure enough, on the way back, I decided to ignore its requests to get off the turnpike early to take local roads, and all of a sudden the ETA would be shorter once it recalculated to the normal turnpike route!

Also, the bridge/tunnel situation in NYC can change dramatically in minutes. The traffic data for these instances simply does not update quick enough.

I think the receiver is worthwhile overall, especially if you aren't checking traffic reports on TV/radio, or are in unfamiliar territory, and most useful for medium commutes. However, for longer trips, it is best taken with a grain of salt, and a local traffic report on the radio.

One last thing. Not sure about the 300 series, but my 660 is very prone to crashes/freezes. Not the biggest deal, requiring a hit of the power button or the reset tab, but one of the functions it most commonly freezes on is pressing the yellow exclaimation "show traffic" button.