Is this the right phone for me?

Hi
I'm thinking about buying this phone, but... with some special details. and I wanted your opinion.

I'm not really looking for a phone, I'm looking to replace my nexus 7 GSM (2012) tablet.
It cannot be something bigger than the N7 (in physical dimensions), it must have 3g connectivity and it has to be an upgrade (better specs).

These requests pretty much clean all the tablets, as only the 7'' and (some) 8'' are small enough and only very few have 3g or 4g.
So I thought of a phablet, and the Z ultra appeared on the search.
I know the screen is smaller, but I don't expect that difference to be a problem. I'll try to find other big phones in a store to compare.

I have a Z1 compact as a phone, and from the looks of it, the Z ultra is exactly the same, only with a bigger screen and battery.
This means the same rom support (cyanogenmod), the same performance (I'm very happy with the Z1 compact on that) and bigger battery and screen for movies and games.

So, am I right, do you think this is a good choice for me?