Interesting comments on advising not to use it, or not trusting it with contrast detect AF. So far I've been using BBF on my X-T20 without an issue - seems to work just like my D7100 does. My only initial problem was forgetting to de-couple my shutter button focus when I assigned AF to the AE-L button.
Anyone have any sources that explain the risks of using BBF on mirrorless cameras?