TomTom One Version 2 or Version 3?

I am looking to buy a new sat nav. I have decided to buy a TomTom One (Regional) but am confused by the different versions available. Version 3 has just been released and a new model would usually be better. However, I'm not too sure. Is the Version 3 a extra-budget TomTom (it does not have bluetooth and does not seem to be compatible with TomTom Home (TomTom website) although some other websites say that it is (Amazon, for example)? On Version 3 the map data comes pre-installed on the hard disk as opposed to an SD card - is this better? Is 'Mapshare' any good or is it just going to enable those of a mischievous nature to introduce inaccuracies?

I would appreciate any information, thanks in advance.