Dizzy, actually no I have never heard of or had first hand experience with a double coated dog suffering of sunburn or heat stroke after being shaved. We had a Newfoundland years and years ago that had a ton of coat (yes Newf's are a double coated breed not recommended to shave). Due to humanity my Sister (a dog groomer) shaved her one year. Rudi hated being groomed, standing on the table to get all the undercoat out and bath were too hard on her as she was about 11 years old. My Sister weighed the pro's and con's of shaving her and decided the pro's out weighed the con's for her. Her first summer shaved she was cooler and happier. She was not skinned when she was shaved as my Sister left about 1 inch all over. My Sister feels that shaving her for the last few years of her life extended her lifespan. There is a time to consider the benefits to the dog rather than anything else. The first year Rudi's coat did not grow back in properly, but after that initial shave she then started growing back properly for the winter. For Rudi it was the best thing we could have done for her.
At the grooming shop my Sister will do as the client wishes (the owners are told the con's of shaving a double coated breed). There are many double coated breeds that have unnatural coats such as Newf's. Years ago a Newf was a wash and go breed with a natural coat that was easy to care for. Now with show breeding, breeders are breeding Newfs to have a ton of coat that normal pet owners cannot keep up with. We groom many Newf's for show and there is a lot of work including scissoring for show, in the States Newf's are scissored all over for show. I personally see a difference in the coat even when it is scissored, it seems to grow back in fluffy etc. With our own Newf's when they were being shown the bib, pants, paws (of course) ears etc were scissored and I can see even now where they were scissored as the coat did not grow back in properly. My Sister still keeps them scissored as they can look pretty scruffy when left au natural.
Also you have to consider the client as well. We have a few Newf's that we do shave off for the owners. These dogs have a ton of coat that even the most diligent owner would have a difficult time keeping mat free. So you then get a Newf develop mats, maybe the owner cannot have their Newf groomed as often as we would like them too and the mats get worse and then a hot spot develops under the mat that the owner doesn't see...summer comes along the hotspot attracts flies as it is now a mess and the flies lay eggs and viola you have a nice litter of maggots. That happens and for me if this is a possibility then it's best the owner have the dog shaved (not skinned). We have seen some Newf's lives improve a great deal after being shaved. Instead of being stinky and left outside they are now part of the family. The owners are now enjoying their dog instead of finding the dog too much work and they are more a part of the family. This is where humanity before vanity comes into play. If it helps improve the quality of life then so be it. These owners have been so happy that they get their Newfs shaved once a year, they can spend more time having fun and enjoying their dog. It's also easier on their pocket books.
My Sister always tells owners that the dogs coat may not come back in properly. The healthier the dog the better chance the coat will come back properly.
For the most part for double coated breeds like Husky's, Shepherds, Collie's etc its easy for us to get all the undercoat out during normal grooming and the dog is comfortable for the entire summer. It just depends on the owner and what the owner wants,they are told the risks involved etc. There have been some breeds that my Sister has shaved that she really tried to talk the owners out of like Lab's, and Golden's but the owner really wanted it done. Most of these owners love their shaved off lab's and Goldens etc as they say it cuts back on shedding and their dogs seem happier etc. We have one Sheltie that we have to shave off due to health issues. The Vet told the owner that the Sheltie had to be shaved. The dogs skin looks much better and the Sheltie is much happier and healthier. We have a lot of Shelties and collies and that is the only one we shave the rest we get all the undercoat out during grooming.
Anyhow that is my take on it. My Sister has never seen any problems other than some dogs the coat does not grow back properly. At the end of the day it's the owners choice, it is after all "their" dog. I personally feel docking and cropping to be far worse than shaving a dog off, after all the dogs coat will grow back in...the tail and ears will never grow back. Plus, there are no pressure points in hair like there are in the tail and ears