I personally would not opt to shave a doublecoated dog. As Shelteez mentioned, when I had my RB collies their skin always felt cool even if they had been laying in the sun. I feel the coat provides protection from sun and insects, and since dogs do not sweat through their skin it is not the same as a human wearing a coat outside in the sun. I think some people tend to think of it as how they would feel if they were wearing heavy clothes out in the sun but their coolant system is different than ours so it's not really the same.

I did use clippers and gave my RB Cody a trim so his hair was a bit shorter and thus easier to keep brushed out so mats wouldn't form up next to his skin and cause hot spots, which he was prone to, but it was not a shave, just a trim.

This is a subject of many differing opinions, but based on my experiences with my two doublecoated rough collies, I personally would not go for an actual shaving. After watching Willie with his black coat lay right out in the sun and then reaching my fingers into his coat to find his skin cool, I was satisfied