My understanding is that in executing a Missed Approach under 1.10.1 (a) or (b), you must immediately track and climb as directed by the plate.
Absolutely NOT!
Under (a) You must follow the track down to the MDA level, and then climb as directed. It may be a level segment, it may be a direct climb, but you still drive down to that point.
You can go missed at anytime during final segment, so to go missed early and direct climb, you may have issues with driving into the DEP ac, or ac crossing procedures.
In case (b) the assumption in the regulation is that you were on the flightpath, and after the MAP/MSA, the radio aid fails. (note during an instrument approach). If this is the case, you are outside of the parameters of what is on the plate, with the missed approach criteria.
You cannot level off below the MDA before the MAPt, if that is what you are saying, you are outside the criteria to be able to climb and have obstacle protection. Want to meet the Tower?
Going missed below the MDA/DA is balked, and outside criteria. As the question is open to the level below MDA, best to get directions from ATC rather than the plate and hope.