21J movements are fine, cheap and good, but (personally) I wouldnt like it to be posing as a tourbillon. If you can afford, get the real thing, its a beauty.
Another thing is, the rep Hublot you shown us at watcheden seems to be of poor quality thou. I suggest taking a look here: The $200-300 are the flux tourby, the $600-700 are the real deal. Some nice videos for you to compare too.
http://www.puretimewatch.com/category/big-bang-tourbillon/
And if you ever wanted to get the real thing, use western union to get a 10% off for a small fee.
Lastly, do a search on tourbillon, there are quite a few thread about them.
Good luck in your hunt
