I have K&N air filters in both my LR3 and LR4. No issues. These are the oil-less variety so no issues with oil fouling the MAF. For what it's worth, they sound better at full throttle . Would I buy them again - doubtful, just because of the overall concerns with the finickyness of these vehicles.
They are not oil-less, simply they came pre oiled from the manufacturer. Eventually they will need cleaning and be re-oiled. This is where the problems start. Fortunately the intervals can be so long (50k miles) that many owners never have to clean and re oil.
Any restriction in the LR4 is not intake related.