It looks as though VW have caught the Mini bug and have realised they can make much better margins by offering a series of over-priced specials.
The Black and White were nicely specified for a reasonable premium, helped by the fact that special white and pearl black were included in the price, but looking at the Groove and Rock version, they seem to offer little extra for a lot more £ - unless I'm missing something.
The Groove up! appears to be a High up! with 16" wheels, special seat fabric and a couple of special colours - including pearl white @ £910 extra!!! They seem to have included the spare wheel as standard, but not the sound pack (which now appears to come as standard on the High up!).
The Rock up! is a High up! with limited colour range (metallic is extra though), stripes, spoilers, skirts, 16" wheels, spare wheel and sports suspension. Unless the VW website is wrong, the stereo in the technical info is the same as in all other up!s. At nearly £13k in basic form, it doesn't bode too well for the price of the up! GT - perhaps part of the delay in launching the GT is to see how far they can go with the price!
A High up! with your choice of options looks like much better value IMHO.