THE 3 forms of heat loss from an object or surface at earth's surface are...

[Climate Realist]

"Over what percentage of earth's surface can latent heat of water vapourisation not play a significant role?"

Quite a large area! Deserts, poles, mountain tops, savannah, urban areas. Anywhere where there is less water.

"I would also note phase changes (latent heat) tranports vast amounts of cold down within the climate system too. ie, snow / ice / frost."

You can't transport "cold" as such. Cold is only how our senses let us know an object or environment has less heat than is comfortable for our bodies. Cold in itself does not exist! Only differing amounts of heat in matter.

I'm not saying that evaporation isn't important. Just that you seem to have something against convection. Greenhouses work by stopping convection, thus trapping a warm body of air that would other wise rise. As does a layer of clouds on a winter night in the UK that prevents heat loss by convection and thus prevents frost.

You shouldn't be thinking of "cold" as a physical entity in itself. But of differing levels of heat. At all temperatures above 0K, all bodies have some heat, i.e. some vibrational energy in their molecular structure.

Latent heat is not really heat, neither is radiation. Both have the potential to release energy as heat but that depends on the conditions the latent heat carrying material or the "thermal" (really LW IR) radiation encounters. Think of them as stored heat and not heat in themselves. Whereas, convected air, which I think has been neglected as a source of heat transport in the rush to nail everything on radiation and thus MMGW really is vibrational molecular kinetic enegry, stuff moving, it is heat. Think of the power in a convection thermal. It can keep heavier than air objects aloft. It has enough power to overcome gravity!