Only partly answers your question but I have the Tom Tom app on my iPhone 4. I just put it in my pocket and with in ear monitors and follow the voice prompts. It's clear, accurate and once you get used to it you don't need to see the screen. I also use it in the car with the tom Tom mount, anyway this Xmas I took out a month subs to the live traffic update. Bloody brilliant, coming back from Devon to Kent it took me round all the normal queues on the A303/M3, recommended. We have TT rider and a 660 at work, I prefer the 660 for map detail but the TT is easier/faster to use, apart from waterproofing/ charging issues TT iPhone app is far superior to to either of them. Food for thought?