It sounds like you are replacing the parts for 'mental' reasons.

I don't think machined parts are necessarily better than MIM.

To assure reliability both would need to be made by quality processes and xrayed for defects.

I doubt you will get parts in either category made with such quality control processes to get the reliability you need.

If you want such reliability buy a glock or M&P, the designs are the current state of the art in high reliability police/professional use.

ANY gun made for the commercial market even with bar stock forged parts won't have modern engineering and quality control behind it.

You won't have a engineer designing it with a MTBF or mean time before failure analysis going on.

Bluntly commercial guns have commercial quality and no one is doing engineering analysis on their products other than to ensure any warranty period is satisfied.