First, the good news: the nuvi 780 acquires its initial position fix faster than the older nuvi 600-series models. After powering on the nuvi 680 (left) and the nuvi 780 (right), the nuvi 780 acquired it's full signal strength almost immediately, thanks to its use of SiRF's InstantFixII Technology.

Within about 30 seconds both the nuvi 680 and 780 indicated full signal strength. So far so good. Tapping and holding the signal strength bar for about 5 seconds brings up the more detailed satellite signal screen, shown below.

Wow - the nuvi 660 showed 12 foot accuracy while the nuvi 780 only got 19 foot accuracy. The nuvi 660 was getting 58% stronger reception. I left both units on in a stationary car and let them numbers settle. Even after 20 minutes the nuvi 660 was receiving between 45% and 60% stronger reception than the nuvi 780.

The reason? Simple: the nuvi 760 uses Garmin's new, slim design that doesn't have the flip-out patch antenna used on the nuvi 300 and 600 series units. Instead, the nuvi 700 has the GPS antenna facing backwards in the rear of the unit instead of having the antenna mounted across the top of the unit. By contrast, Magellan's Maestro GPS units have the antenna installed on the top of the unit where it's easier to have a clear view of the sky.

I do like the new features the 700-series nuvis bring to the table, and overall the reception on the nuvi 780 was still excellent (I had no problem using the unit in downtown Manhattan, snow storms, and behind tall buildings). But there's no denying the nuvi 780 gets weaker GPS signal reception than the nuvi 680.