You're experience is a little flawed though, in that you're criticising an entirely different quilt made from an entirely different material.
You're misinterpreting the Amazon reviews. I thought that at first and decided to give it a miss, but when you separate out the reviews relating t this down version you'll find not one single review mentioning overheating. All but one are 5 star, and the other's 4 star. All the negative reviews relate to the polyester microfibre version Amazon have lumped together with this natural down version.
Not in my experience. I use merino wool topper over mattress and have a £150 Tempur pillow but I get on better with micro fibre quilt and merino wool throw if I need extra warmth. But yes you are right it is personal choice. We are all different in many ways.
Can you post a link for where you bought your silk duvet? And, yes, I'd def' like to know what is a fair price for a king size silk duvet? Too many different Tog duvets, v. bored with too hot/too cold palaver - time for the middle ground 😴
Personal choice, isn't it. Natural materials such as down are always going to be more expensive than plastic fibres. They're also much more breathable and less sweaty.