I have been told that when the switch over occurs in 2015 sat navs will no longer function, this is why many of them have become alot more affordable, which they have to a degree.
This may apply to some old ones me thinks but surely not the new ones. I am looking to possible buy the TomTom 5150 as people seem to recommend it quite highly.
How true is this switch over malarcky?
The satnav function of a satnav works by detecting signals from orbiting satellites, needs minimum of three satellites to get a position. The analogue/digital switch over of terrestrial tv/radio has no bearing on satnav function.
Don’t know if traffic updates could be affected but would think that this is digital signal.
As said the digital radio switch-over in 2015 (if it takes place) has nothing to do with sat-navs which work by GPS.
I don’t use traffic updates but I’m pretty sure they are transmitted by sending digital data over a mobile phone 3G network.
On a side note, the UK together with the rest of Europe are spending billions of €s developing a new GPS system called “Galileo” which is due to come into service at-least in parts in 2014, so rather than sat-navs being redundant the hope is that they will gradually become more accurate 
I didn’t think this sounded correct when I heard it but it was from someone I couldn’t argue with or educate either. Thanks once again!