Which TomTom?

[Etretat]

My TomTom 720 has finally died, It's been good and although TomTom Home leaves a lot to be desired I can work it so not a problem.
There seem to be many TomTom models out there. I'm not after the cheapest or the dearest but I would like to be able to compare the various models available, so far I haven't been able to find anywhere with this information.
Is it just me?

[stemll]

http://tomtom.com/en_gb/drive/car/#productLineup

Start 40/50/60 (4", 5", 6" screen). Lifetime Europe maps, no traffic or speed cameras. £100/£120/£140

Go 51/61. Speed cameras and traffic. Lifetime worldwide maps. Link to a smartphone for data. £150/£170

Go 510/510. As 51/61 but with screen like a smartphone with pinch/zoom/swipe. Magnetic mount. £170/£200 but on offer at Halfords so cheaper than 51.

Go 5100/6100. As 510/610 but built in SIM for data (including searching for POIs and so on) £260/£300

TomTom said:

Lifetime – this is the useful life of the device, which means the period of time that TomTom continues to support your device with software updates, services, content or accessories. A device will have reached the end of its life when none of these are available any more. The useful life of the smartphone app means the period of time that TomTom continues to support the app with updates.

http://uk.support.tomtom.com/app/glossary/letter/L