My test on customer's phone.

here

The fruitphone 6 pawns the z3 at being much better and quicker in autofocus and excels in lowlight conditions.  I'm afraid the only advantage the z3 has over the fruitphone is at better photo details when picture opened on large screens ie desktop or laptop.
Overall the fruitphones' camera pawns the z3 even though with a much lower megapixel camera.

I own both. The fruitplus as well.

If picture taking is your main priority, I would suggest you go for the fruitphone. The shutter speed and autofocus on the fruitphone is just superb. Sorry z3 fans.

However you cant impress your friends by bringing the fruitphone to the pool like the z3.

Hot swap