Is it possilbe turn off individual groups of POI's notifications. For instance, I have the safety cameras POI's as well as the McDonald's. I always want to be notified where the safety cameras are, but only want to know where the McDonald's are when I want one? I can only see an option to turn on/off all the POI's.
I have a Nuvi 760 and it has the same limitations as you describe. Rather than be irritated by every announcement or continual beeping, I deleted the mp3 files on all but the traffic alerts and turned the POI alert function off. When I want to go to a McDonald's, etc. I search for it in the POI's I've loaded and hit the 'go to' button whereupon it will voice guide me to the closest one. Hope this helps.
How about loading a full set to SD card and a more limited permanent set to the device itself. Then leave out the SD normally but when the munchies hit, use the SD version with the extras.
Not really a switch though.
To try, have the extras only on SD and traffic in device and see if you get a merged set.