I love the beauty of the tricolor coat, but wow, that black fur gets hot in the sun -- even the April sun of central Washington, which is a near-desert -- no snow for making corgicicles here, no water to soak them -- I wonder if the paler reds find it easier to stay cool in hot sun? I suppose heat was seldom a big issue in Wales.
This might be a consideration for people living in hot places with much sun and little shade. Rarely an issue for us, but when it is, they feel it.
UPDATE: I've found hand-feeding mountain snow, when available, a great way to cool the dog. If the dog eats it eagerly, that's an indication that they're hot.