There would have been no reason for Apple to list 1700 in the specs because it's not being utilized. It also would be a dead giveaway that they were going to T-Mobile.
Not just that, something as basic as processor speed hasn't even been revealed yet lol. Most review sites are just guessing btwn. 800-1000mhz. Apple is so good at secrets, I wouldn't be surprised at all if it had the 1700 band.