XM traffic vs. FM Traffic

I am considering a GPS unit mostly for the real time traffic. I make 2-3
trips to Connecticut a month plus other driving around the New York area,
makes sense to have. I already have an XM account as I have a new GM
vehicle.
How good is the traffic monitoring on these units and which one works best.
Thanks

I have the XM traffic service for my Garmin 2730 because I commute into
downtown a lot and like to know about accident-induced traffic snarls
before I run into them. We don't have traffic flow data for our city,
so I can't comment on that.

What I've noticed is that incident reporting is pretty prompt. I have
seen accidents pop up on the traffic reporting screen before I have heard
about them on the radio. It's also pretty thorough: we get incident
reports for everything from accidents to salled vehicles to hazardous
sun glare. The indcident reports generally say how many (and which)
lanes are affected.

I have also noticed that incidents reports tend to stay around even after
the incident has been cleared, which makes sense when you realize that
traffic backups can persist long after an accident or whatever has been
cleared.

Overall, I'm prety satisfied. But, the caveat is that you have to
actually /look/ at the traffic report screen to see what's going on.
That means reading, and that can be danerous. This is best done before
you leave the house or by someone else in the car. Waiting for the
incident icons to show up on the moving map display means it's too
late to avoid what you're running into, and the icons are a poor
substitute for the information.

As a closing comment, the XM traffic data is broadcasted continually,
but it may take up to a minute for your city's data to come up. With
the 2730, the traffic data isn't "saved" when you turn off the unit, so
at every start up you have to wait a minute or so before your local
traffic data comes up.


Cheers,
John

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Oh...one more note. If you alrady have the XM service, then adding
XM traffic will be pretty cost effective. Note, however, that an
aftermarket GPS receiver is its own radio, and the XM rules are that
you have to pay for it as an additional radio. It's not expensive to
have multiple subscriptions, but it's not free, either.

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)