The weight attributed to patient values in determining best interests

In W v M and Others (Re M) the Court of Protection considered whether withdrawal of artificial nutrition and hydration was in the best interests of a person in minimally conscious state. The Mental Capacity Act 2005 states that in determining best interests the decision-maker must consider, so far as is reasonably ascertainable, the patient's wishes, feelings, beliefs and values. Baker J. indicated that a high level of specificity is required in order to attribute significant weight to these factors. It is preservation of life which carries substantial weight in the best interests' balance sheet. Could the (prior) values of a patient ever meet the probative standard necessary to offset the weight accorded to preservation of life? Rather than referencing the patient's values to specific circumstances and treatments they could be more effectively considered as part of the patient narrative, how the patient would want her life story to continue/cease.