Hi Hypnos,
While “feel” itself is very subjective … what you are describing is a function of what I commonly refer to as PPP (Posture and alignment, Pressure relief, and Personal preferences).
While it’s not necessary to know this because careful testing using the testing guidelines in the tutorial will do a good job of telling you which mattresses are suitable for you without having to know the “why” behind the “what” … if you are interested there is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
Phoenix