I guess you're not reading my
posts! I've been DIY BKTing for 3 years without any appreciable damage. I can only recommend QOD original formula, though. I haven't used any others. I love it! I'll never purposely stop BKTing my hair.
Everyone is afraid of the aldehydes and the high heat required for the process. I have super baby fine hair, and I have no hair breakage. It does make your hair super soft, which can be a problem, again, depending upon your beginning hair texture and your desired results. I'm satisfied with always wearing my hair curly, so it does't matter much that my hair is too soft to hold a curling iron curl.
The results can be permanent, and that's what some people don't like. There is so much misinformation swirling around and, sadly, professional stylists aren't really that much more informed than the average client--sometimes less. Many I know haven't even heard of BKT and those who have don't know enough about it to even be dangerous.