Have you ever been to Nathia gali ? either from Murree or from Abbotabad ?
Thats' where you need the power of the 1.6 , as the 1.3 you will be using with only first gear.
I have just yesterday returned from that area with corolla 1.3, and my thoughts on the matter i have presented.
Now whether the 1.6 is brand new or the old model, I don't think that it matters much.