Knix/Thinx Period Underwear...Thoughts?

OK so my sister has not really convinced me I would say. But she is a type of woman that does not use tampons for her period. She will use a pad and mainly only pad for everything. Her logic is that Using a tampon can cause the bacteria that your menstrual cycle is providing to stay in your vaginal canal until you take it out and that’s not healthy. In some once I do agree with her especially after her long hair long conversations about it as well as her really incited opinion on it. So it got me thinking. Should I start using period Underwear? If some of you ladies don’t know period underwear is basically for the women that like to “Free Flow”. No tampons no pads just your underwear. The underwear have a lining that is embedded in the underwear to catch all of your menstrual cycle flows and discharge. So I bought my first pair about two weeks ago from a company called Knix. I bought it and hope that one next period and see how it goes. I wanted to get other ladies thoughts on period underwear’s. Do you use them do you like them what’s your thoughts?