I'm sorry to have to dispell whatever the dealer might have told you, but the LR3 is in fact a Discovery, not a Range Rover. (It's only in the US that they've dropped the Discovery name from Discovery LR3).
Having said that, from what I've read to date, it should be a very capable off-road vehicle. If it's up to the Mk III (L422) Range Rover remains to be seen. Then again, taking a $75000 vehicle off-road takes some very calm nerves, or very understanding insurance.