Agree that P38 do not rot just look at the quantity of body shells and chassis that are for sale on Ebay.
The brakes are exactly the same as a Disco 2. Same disks, pads and calipers I know because I have swapped bits around. The Air suspension should be the same as a classic because the LSE was used as a test bed during the design phase of the P38. The V8's on the pre 2000 models are virtually the same but the 4.6's have obviously been stretched close to the limit.
The BECM is a major issue. I had that go on my 2000 model which, because of my difficult financial circumstances, caused me to run a Mondeo for 9 months before I bought the Disco. I swore I would never have another P38 but that was then and this is now.