So I will ask the question again: Is it legal for a private pilot to descend (in IMC) to say (for the sake of this thread) 400' MDH on a DIY approach?
Common sense would dictate that you do not descend below 800 feet which is the non-precision system minima plus 200 for luck (and then sanity check that against the local terrain and obstacles within 25 miles circumference).
Also agree that you should not play "cloud roullette" but should get a RIS OR RAS.
Other caveats - Have at least an IMC rating, preferrably IR, be current and proficient, have a plan B and a Plan C (i.e. know where your alternates are and make sure that you can reach them and that they have VFR weather or a precision approach which is forecast to be well above minimums (legal and personal).
Plan well in advance and don't get caught out !