I know AR077 is a diesel but what about the rest of you? And how is your mileage and experience with DEF?
To answer your first question (second question answered below), I ordered a 5-seater since we had no need for the third row of seats. That also gave us extra storage space under the cargo floor but limited us to the HSE since the HSE Lux only came with 3-row seating. The stock 255/55-20 Goodyear Eagle tires on 20" x 8.5" OEM wheels were sub-optimal for off road activity so, at 16,000 miles, I swapped them out (including the spare) for 285/50-20 Nitto Terra Grappler G2s mounted on 20" x 9.5" Redbourne wheels (no lift required and no clearance problems). Apart from the off-road performance aspect, the wider wheels and tires came with a huge improvement in paved street road holding and maneuverability.
The main reason I ordered a Discovery 5 before they were even in country was the availability of the same big Td6 engine that was only otherwise available at the time in the Range Rover and Range Rover Sport. For several reasons, diesels are preferable to gasoline engines in an overlanding environment. Diesel advantages include the following:
1. Low risk of overheating. A properly maintained diesel engine is impervious to hot weather (it's not a proper summer in Las Vegas if we don't see 115 degrees in July).
2. Fuel economy. I don't know what gasoline D5s are seeing but my Td6 gets >26mpg with the cruise control set on 80mph (the speed limit on I-15 between St George and Salt Lake City). Surface street mileage is ~21mpg. DEF is easy to add when the warning light comes on and four gallons (~$50) lasts 4,000 miles.
3. High torque at low RPM (which is optimal when off-roading) as opposed to revving the engine (and wasting fuel) to maximize gasoline engine torque.
4. Safety. Diesel fuel is much less volatile than gasoline, so it's less hazardous to carry multiple containers of spare fuel when overlanding.
I like the looks and features of the previous generation of Land Rover LRs but never considered getting one since a diesel option was not available. It's sad to see diesels being phased out and replaced by battery power.