While the tow-bar is a clever design in that it can be removed completely, there seems to be major flaws with the standard tow-bar:

• Tow-bar height does not adjust with suspension height (automatically, or manually).
  
• The Tow-bar is too low for off-road trailers, and it is not possible to adjust the tow-bar.
  

 Aftermarket tow-bars are available (eg BRS), but it would have been nice if the job was done properly from the start by Land Rover's design team.

The suspension will lower from Offroad mode to Normal mode when the speed exceeds 50km/h (verified on a 2007 TDV6 S).

This can cause problems especially when driving in sand, and picking up speed to get up a dune.  

A very good safety device, but the beeping is so annoying (eg when moving a trailer around & need to take safety belt off).
But it can be disabled!  the same system as applies to Fords works - simply turn ignition on then rapidly (within 1 min) put the safety belt in & out of the clip 9 times! On the 9th time the safety belt light will stay on for a while & then after that you still get the safety belt light but not the "beep" One caution... I don't yet know how to re-enable the "beep" 

Source: disco3.co.uk  

I have verified this yet on my MY07.

It is a challenge to find suitable tyres for the Discovery 3. The TDV6 S model has 17" rims (South Africa).