Boomerangben is right about some of the pilots here, which I why I dislike the blanket comments being made about a transition into IMC being dangerous.
The question is, what is the "average private flyer"? It is a low hour PPL, about 20 hours/year according to one CAA man I spoke to recently. What does this mean for our discussion? Nothing much. A PPL shouldn't be in a cloud in the first place, and if he gets into one he will probably lose it.
Perhaps you meant "average private flyer with an IMCR" or "average private flyer with an IR". I am not trying to be difficult or stupidly pedantic here, but there is no doubt that the average IMCR holder is lapsed! As is the average IR holder! How many of the instructors at your local school, who once had an IR, still have a valid IR? Almost nobody will keep an IR valid unless they fly (or plan to fly) commercially, or fly regularly into Europe and need to be able to do so IFR.
The currency of the average IMCR or IR holder (private ops obviously) is just as piss poor as the currency of the average plain PPL holder. This is because most people that hang in GA today can't afford to do 100-300 hours/year, and they can't afford to buy the nice well equipped plane which is required for safe IFR.
There are IMCR pilots (like myself) who fly IFR anytime, in IMC if necessary, and don't bat an eyelid. The issues are 0C below the MSA, etc. (so the example given with someone's elevator trim freezing is daft; if one climbs into IMC and OAT is < 0C then one can expect this, which is why 0C below the MSA continues to be a planning issue even if VMC is expected en-route) But IMC itself is a total non-event and the VMC/IMC transition might be done 10x in one short flight.