Discos are over rated Chelsea Tractors from a company that has lost the plot. There is no requirement for air suspension regarding the number of passengers, coil springs are more than satisfactory. Furthermore , a garage cannot repair or maintain a vehicle to higher standard than what the manufacturer produced.
If you want to know what sort of Four Wheel Drive vehicle you need, then right down your requirements and start looking underneath some of these four wheel drives. X - trails might be reliable on roads and dust tracks, but I could snap the suspension with my little finger. Thin flimsy arms and tie bars that have no load capacity. There is a photo in a L/Rover Series One magazine of X trails been recovered out of mud by S1's.
The bigger japanese stuff like Navaros & Warriors ride and drive very nice but are on torsion bar suspension on the front axle, which has limited movement. They are also very large heavy things that drink fuel and unsuitable for tight off road spots.
There is only one all round decent 7 seat four wheel drive, which you cannot buy new anymore, Land Rover 90 County with TDi 200 or 300 engines. Just look at the second hand values. If I am not mistaken, it was Her Majesty's favourite when driven around the estate, (Blue Peter, going to the Post Office in the 1970s).
Also, if you want more capacity, then put a Sankey trailer on the back when required. Had mine over eight years, no problems and it works for a living.
Or buy a Toyota Land Cruiser. Land Rover, are you listening ? That new Range Rover thing is a Bankers Hand Bag.