Defo keep the Moto G updated should you run into an emergency again, it's a bonus that it recognised your 128GB which is very handy
That's quite surprising you would think that a company like Sony would have a better repair portal. At least you get a tracking number which is better than nothing, I certainly hope that there's an engineers letter in box. I think there's also another update waiting for you to install if you haven't done so already - mine is on v23.01.A.5.77 which was installed a couple of weeks ago.
Keep us posted Mark with your thoughts.
It is buggy for sure and 4.4.4 is a god send compared to it, it may look beautiful, I like all the animations but things like the memory leak and Wifi bugs and the battery drain just take the shine off Lollipop. Although I've read somewhere that Google will be releasing 5.1 sometime in Feb which promises to fix all the major bugs that they are aware of.
Good move buying the Z3 from Amazon if you don't like it you can always send it back because of their excellent returns policy.
You do get used to the size eventually, as initially I thought it was a little too tall for me but I've got the hang of managing the Z3 and mostly use it with one hand.
As for unlocking the bootloader and it affecting the camera quality there's a mod on XDA that negates the issue.
Have a look on the link below: