I use a nuvi 1490.
I have found that there is more to the zumo than you noted.
An important difference exists in the Bluetooth capability.
The Nuvi has Bluetooth, but it functions totally differently (because it's for car use) than the way that we need it to operate on a motorcycle.
The crux of it is that there are many different Bluetooth protocols and the units are built to support the protocols needed for the purpose, not *every* protocol.
The car units use BT to connect to your phone, and the GPS acts as a Speakerphone in your car.
This type of BT connection is useless on a MC.
MOST car units essentially take your phone's audio and play it through the GPS's speaker.
On the MC we need the GPS to output it's audio to the MC, or to our BT headsets.
Most Nuvi models do not output their audio at all. Most don't even have a headphone jack! Again, they are fancy speakerphones when used in a car.
The Zumos otoh, support specific BT protocols to output audio, connect the phone, control the phone, connect to BT headsets, control the GPS, control the MP3 player and output the music.
And they don't do speakerphone.
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