ThePuristS appears to have deleted all older feature articles and pictures. In 2004, I published a rather volumiinous review of the UN GMT Perpetual, how it works and how it is used. For me, it is still the most user-friendly perpetual calendar on the market.
When the original Freak was launched, there was a fierce discussion whether it should be classified as a carrousel or a tourbillon. The majority later agreed on a designation as carrousel.
The UN Skeleton Tourbillon Manufacture is a classic tourbillon (without the intermediate gear), but with a self-developed silicium escapement.
Apart from the different price point, I would opt for the Freak, since this is a really unique timepiece. However, for everyday wear, the perpetual calendar would be the perfect choice.

Regarding the difference between a tourbillon and a carrousel, here is a very nice video from Blancpain, demonstrating these differences: [technical difficulties with the video, check back later]
Marcus