Not sure what your point is. The ANVS on the Q400 is a real POS. Not sure about recent times, but when I was at flybe the system was normally inop. It would fail, get deferred forever, and then the new box would fail within a week or so. The aircraft is very noisy without it.
There were also major issues with prop balance. When I was there, the props had to be balanced once a week to keep the vibration under control
The Q400 is also a cheap aircraft rather than a good one. It would be dead and buried if flybe hadn't bought it, and they only did so because they got it at fire sale prices. Bombardier were going to close the factory until flybe came along - nobody else wanted it and there have been a lot of issues with it.