It is hard to decipher the fly-aways that I've read about. Nearly every thread has people who jump on with their favorite 'other' system (meaning - they have an agenda) or who have made rookie mistakes (leaving the GoPro network on, not knowing what the lights from the NAZA mean but swearing they did everything right, etc). Often, in a thread that has dozens of posts, there is only one or two that seem to have experienced legitimate issues.
IMHO - The F-series appears to have a reasonably good track record and the FangsCPO post that says this might be due to better piloting/experience is likely.