well, i couldn't try the XK-2 but i heard it in mp3 (downloaded from Keyboard Magazine site) and to me it has a better "attack" noise than the Vk-7 but... the VK-7 is MUCH better as it sounds warm, big, and real...
the XK-2 is so digital sounding, cold, and thin...
ah, the overdrive on the VK-7 is VERY good!
The only important improvement the XK-2 has, are the waterfall keys: but only if you already own a hammond... otherwise the keyboard on the VK-7 is the best i ever played...
OPS... I HAVE A VK-7!!!