Just to add my input to the thread, the rear wear sensor of my 2013 LR4 with almost 21K miles went off yesterday. I assumed it was the rear sensor because: a) at my 15K miles service freebie the local LR Encino dealer informed me that the rear pads were down to 4mm and they "offered" to replace them - no discs - for $600. I laughed and told them I'd take my chances elsewhere, b) I could hear a faint squeal from the rear brakes area at low speed when stopping since about a week ago, and c) I cheated and checked with my IIDTool.
Today I took the car to my trusty LR indy mechanic down the street, the rear pads were down to 2mm, the minimum s/b 3 (out of 10 when new.) They installed new OEM ones for about $270, including new wear sensor, shop supplies / anti-squeal, tax and labor. Very honest IMHO, considering that reputable shops here (SoCal) charge $120/hr and up. Discs are just fine. Front pads - which I kinda expected to wear out first, honestly - still have 5mm left out of 12 - so probably another 5-7K miles or so to go before I'll be due for replacement of those. I drive A LOT obviously, a fairly even mix of highway and city with some off-roading thrown in. I've also added a good 300+ lbs of sprung weight to the car between second battery, rock sliders and other underbody protection. Overall, no nasty surprises so far.