I'm very, very tempted to go to the Passport when my Z10 contract expires in February 2015, for all the reasons mentioned above.
However if battery life is a problem for you on the Z10, buy the 4,500 Mah battery + cover that is available on eBay.uk and presumably elsewhere for a mere GBP 18.00. It adds a bit of weight and thickness (which I have quickly got used to and like) but the battery life is now phenomenal. In fact it is so good that I have bought a second battery, so I can now go for days without having to plug into a charger.