With the advent of 'CDA'approaches the FAA in regard to terps agreed to the 'Go around' at MDA providing that the 'sag' aspect was reviewed in training(one wonders about the 'sag' at DH-thats why you leave the gear until'posative rate')...
Ergo Carriers ADD an additional buffer.Generally 50',but some also consider Weight,Temperature,and Abnormals such as engine out performance(+100")