The ACH depends on aircraft type, WAT and pilot experience.
For the brand new MEP rated pilot in general we teach an ACH of 400ft. At the subsequent renewal 1 year later, again depending on type and experience there may be a reduction in this figure but the lowest used is 200ft.
However, we teach that an engine failure in a twin is an emergency and a mayday call must be made. This can help to reduce the chances of making a missed approach.
For instrument pilots (including IMC rated pilots who fly MEP) the same ACH applies.
Our and the CAA's policy is that if possible an engine out approach in IMC should be avoided. If that is not possible then the minima to be used are the higher of the procedure minima or the ACH. In other words we do not change the ACH just because the pilot is instrument rated it depends on their experience on class and type.
BEagle.....basically don't reduce below blue line or extend landing flap until a landing is assured (or comitted) is the only requirement......thus having an ACH of 400ft not only ensures that a missed approach can be made safely but it also gives time and height for the inexperienced pilot who is landing to extend the landing stage of flap and get things set up without being in a rush which they could end up in if 200ft was used.
Regards,
DFC