Um… 
So yet another eBay bargain came my way.
I won’t go in to the details of the acquisition but suffice to say the seller didn’t know the difference between the X3 and the Z3. And they sure as hell weren’t aware of the price difference 
The ‘regular’ Inspire 1 ships with the Zenmuse X3, on par with that of the Mavic Pro 
DJI also make a Z3, with the ‘Z’ standing for ‘Zoom’.
DJI promote the Z3 camera as offering a 7x zoom level.
Strangely though, it’s spilt.
The 7X zoom is made by pairing a 3.5x optical zoom with a 2x digital zoom.
Weird, eh? Why not just sell it as what it is, a 3.5x optical zoom? Anyway…
DJI also market the x2 digital zoom as being ‘lossless’, which in my brief back garden tests today, I’d strangely have to agree with.
The Z3 camera (vs the X3) also features the same Sony 1/2.3" sensor as the Inspire 1 V2.0 and the Phantom 4. The lens is 22–77mm Equivalent F2.8 (Wide) vs the X3 20mm (35mm format equivalent).
Anyway, never mind the specs! On to the real world observations 
The Z3 is physically larger than the X3. The case is disproportionately larger!
However, DJI clearly planned this as by taking out a piece of removable foam from the case, the Z3 box fits perfectly.
Some more camera size comparisons:
And when fitted to the Inspire, the ground clearance is also notably reduced (sorry, bad angles):
You’ll need a landing pad.
Um… one that it’ll fit on 
Another immediate observation, that of additional buttons in the GO app!
I now have a green ‘focus’ box! The X3 doesn’t have auto-focus… So I can now touch anywhere on the screen to focus on the that area, exactly like the Mavic Pro does 
Taping on the green box icon switches modes back to the traditional ‘Exposure’ mode that the X3 has.
You’ll also note two extra buttons the ‘T’ and the ‘W’ - these control the zoom level, just hold your finger on the relevant button to zoom in or out:
Clever shit
Here are some zoom examples for you. They are screen shots from the CSU, not from the SD card so ignore the quality
Sat on the floor of the garden, no zoom:
Then zoomed in approx half way:
And finally, the full x7 zoom:
I’ll do a better zoom comparison next time I have it up in the air, but so far, I’m pretty impressed. Especially now I have the familiar ‘tap screen to focus on area’