My apologies as I cannot answer your question about the DME. I find it odd that Serra de Sintra has shrunk by 269' which seems an unusually large correction to a small hill.
Edit to add (in the interests of trying to be at least a little helpful) that with regard to this:
this is only a non-precision approach and our missed approach segment can only be initiated by reaching the missed approach point and not reaching the DA/H.
If the approach is flown with a CDFA then you can use the DH/DA as the point to start a missed approach.