In the Uk, we have a coil model as standard. It is called the Base seat 5. It has a 6 speed manual, high and low range but no terrain response.
Many of the coil owners have had to fit lift kits to use them off road properly. There is a thread on Disco3.co.uk about a guy asking what kit's are good.
Purely because he drove a mild off road trail and the bottom was catching on the ground, while those with "Air" didn't.
I have driven the trail myself and it's actually a very easy one. My group did it in the dark as well..
He is talking about going for either a 30mm or 50mm lift.
But also regrets not getting a model with "Air" in the first place.
I have also found a thread started by Nwoods, who had one of the 25 coil models in the US. He was asking back in 2006 for a lift kit.
He said that the articulation difference was 13 inches for air, and 7-8 inches for coil in standard spec.
Personally, i don't see a need to revert back. The only benefit is being able to run above 30mph in off road height without the warning bong going off.
If you need more space, stick the rods in or buy and plug in a IID tool to lift the car up, then lower it back down when you have finished off roading.
I would be more concerned about protecting the underside with plates etc.
A mate had his D3 bottom out on some rocks, which damaged the TC, which landed him a £1000 bill to buy a new one. He fitted it himself on the drive.
We are now designing our own sliders and plates because of that.
You do have more companies offering protection in the US, in the UK, we have the Devon D44 range, which is £1344 to buy all the plates but comes with "Britpart" Sliders, which are rubbish. Or the Prospeed plates and sliders, but they are over £2000 for the lot.
Which is big money to ask for plates. So will be seeing how your's look in relation to the ones i'm drawing up. I've looked the the Prospeed, the D44 range, Rasta, Tactile rover's and a few others and have made up a design from looking at the strengths and weaknesses of theirs.