I suspect that too much heat (whatever level that is) kills the "live" (active) enzymes and can destroy the vitamins in raw honey much like cooking food can destroy vitamins in it.
Did some checking on "sugar is sugar" and this is what I found:
Source: Bee Pollen, Royal Jelly, Propolis and Honey by Rita Elkins, M.H.
Raw honey is high in nutrition and is a living food which contains proteins, carbohydrates, hormones, organic acids and antimicrobial compounds, live enzymes, vitamins, minerals and trace elements. It also has medicinal value internally and externally and aids the body in absorption of minerals.
White sugar is refined and is a dead substance with no vitamins or minerals. It has no nutritional value and is linked with development of carcinogens.
Honey is mainly glucose and fructose which are simple sugars. White sugar is sucrose and requires additional processing to be digested. Honey glucose increases the body's uptake of minerals like zinc, calcium and magnesium, but white sugar can leech them. White sugar inhibits intake of calcium thus weakening bones and blocking growth.
Honey supplies instant energy without the insulin surge that white sugar causes.
This last statement alone tells me sugar and honey are not the same. The body handles it differently. As far as diabetics are concerned, yes, they should use honey in moderation and avoid all white sugar. (I guess we all should for that matter!)