The 550 has worked for me very well for a year or so. I use it in car and on bike both. Customer support has also been very good, I had one unit die on me and had a new one in my hand within 2 days. The 550 just received the v3.80 software update and new GPS+Bluetooth firmware, so it is not yet forgotten by factory.kjazz said:
But it is true that the design is over a year old, so some update might appear soon. I think the Nuvi range has updated once already, so the same updates might appear on the Zumo range soon.