There is of course a practical consideration, one can hardly expect a pilot to remain aloft because he can not satisfy the MDH. It is important that s/he can descend safely, regardless of cloud base and visibility.
Having said that from my casual observations I suspect that the vast majority of PPL/IMC holders are not current and don't fly in IMC or if they do depend on the autopilot (there is nothing wrong with using the autopilot provided the pilot can also fly hands on). The IR is a package it concerns more than simply flying. Weather (and its effect on the flight and aeroplane) is studied in some detail, far in excess of what an IMC pilot studies. A pilot having to use his rating below the minimums (whether IR or IMC) has probably not prepared adequately and may not know how to.
There is a tendency that the IMC rating will become a get out of jail card. Too often an IMC instructor renewing a PPL's rating is keen to demonstrate how to perform procedural approaches.
For what it's worth I am also a believer in the 500/600ft min for an IMC and perhaps equally controversially that it should only be used in the UK airspace. There are some that believe it can be used abroad to fly above cloud.
Last edited by bpilatus; 8th March 2006 at 06:41.