Even with 20+ years of development experience, Monday mornings are hard...

gistfile1.txt

object newValueInType = newValue;
string newValueAsString = newValue as string;
if(type == typeof(DateTimeOffset))
{
	newValueInType = DateTimeOffset.Parse(newValueAsString);
}
if(type == typeof(Guid))
{
	newValueInType = Guid.Parse(newValueAsString);
}
if(type == typeof(TimeSpan))
{
	newValueInType = TimeSpan.Parse(newValueAsString);
}
else
{
	newValueInType = Convert.ChangeType(newValue, type);
}
_defaultsPerType[type] = newValueInType;

This code has a silly bug of the type one only writes on Monday mornings... I know the code is not stellar, type related code is always a mess as there's no real solid way to test for types other than with Type.GetTypeCode which returns an enum which doesn't contain some value types like Guid ;)

Cant agree more with you about Monday.