I'll answer my own question then, as I managed to pick-up an elite with all the trimmings cheap.
The two tents see identical in most ways, but there are a couple of small, but not insignificant changes.
So the biggest change is the nightfall sleeping pods. The Elite has standard sleeping pods which are made from a light coloured and light weight fabric which lets light through. The Nightfall has Hi Gears nightfall sleeping pods which are made from a dark coloured material which seems to block out the majority of light, meaning the early morning or light night sun will not keep you awake or wake you up. Great if you have young kids who come alive with the light.
The second of what I think is a significant change is that the sleeping pod ends of the tent have air vents just above ground level, allowing resh are to circulate, and hugely reducing condensation. The elite just has the large vents at either end, same as the nightfall.
The last change (that I've found so far) is the opening for the electric hookup. This isn't as significant as the first two, but it's handy. The nightfall comes with a hookup opening at both sides of the tent, whereas the Elite only has one opening.
Now I'm not sure if this is a change, or something the previous owner has done, but the Elite came with old fashioned wire tent pegs, whereas the Nightfall came with a variety for different jobs, a set of V shaped steel pegs to anchor the groundsheet ends, and then two sets of colour coded V shaped plastic pegs.
Overall we feel the upgrades are significant enough for us to stick with the Nightfall, especially having a young child.
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