[Crowl]

One of the new models is both smaller and lower specced than existing ones so its not that unlikely that they would use a lower number for it.

As far as getting rid of devices, maybe the 600 is actually intended to replace the 700 as well as the 505, take a look at what they did with the playstation designs as time went by, they phased out the stuff that would cut costs and slimmed down the designs.