The MDA has been designed decennia ago when aircraft were still driven by props. In these times, you descended to MDA and kept that altitude until visual or at the MAP nowadays, nearly all companies do a CDA. based on the DME/altitude readings on the profile. it is therefore considered that an MDA is in fact a DA.
As previously mentioned, the DA and MDA will be the same in the new procedures. No need to add this 50'.
Operating illegally?! Don't make me laugh! Our OM is approved by a major EASA state and my company is well known for its good standards.