I like the Bangle butt too...
On the debate hardtop vs softtop... The rear window does not look like it is integrated in the roof, and the trunk is not one big element but two elements, which supports the theory that it will be a soft top (a hard top needs the whole trunk to open reverse, while a soft top can do with just a part, like in the current model). However, the fact that these first spy shots already show a 'vert, support the theory there will only be one model: a coupe/convertible, where - like the new Z4 - two models will be replaced by one model that can do both functions.
2006 Interlagos Blue BMW Z4 M Roadster