Based on the manual I doubt it. But if the sales stuff is wrong, maybe the manual is wrong...
It says it has three channels, but no mention of extra sensors, or changing the channel really.
The I600 says it comes with a THGN800 which definitely does humidity. Seems to be on liquidation for about the same price. and 600 is better than 300, if this is the type of station you are really looking for.
Andrew