-snip-
So fro 600 to 1300 dollars in 6 months, My prediction is for BTC to hit $1500 in 30 days. That's my logic!
If it doesn't, I you have my word that I will not try to predict the future again, now where did I put my crystal ball....
Using bitcoin logic : the price broke the $1500 barrier in 1 week in the most exchanges without counting bitfinex of course (+$1600)
More predictions please

Most exchanges have crossed the $1500 barrier. Very few stay within that, soon those exchanges too might quote a higher price. On an average the price on exchanges were found around $1570. So the bitfinex variation is just the different approach to overcome the ongoing problem with the exchange.