I have a silk one and have to say it's really great, I've used it in the UK and Norway to up the rating of my bag, which it does albeit only marginally but hey every little counts (I run cold), I've also used it in South Africa and Sri Lanka as the only thing I slept in, very very cool and no mosquitoes got through it even in the jungle where the air teemed with them.
Such a tiny piece of kit but oh so worth it, I now consider it a firm friend.