There were a couple really odd behaviours in the inital setup of Betaflight that never happened with iNav, the worst being some sort of windup in ANGLE where a resonance developed and then the quad decided to start climbing even after chopping throttle to zero.
I had this happen several times with betaflight back when they introduced airmode. There is a serious flaw in airmode that can cause it to "fly away" under the perfect storm of conditions. Almost lost a lot of skin one time (got lucky with scratches), and had to drop from 80' after arming with another.
Every firmware seems to have it's strengths and weaknesses....