My old Grob Speed Astir II (G104) had a benign spiral mode that was actually outlined in the flight manual. It worked.

My LS-8 will not hold a benign spiral. It begins a series of pitch downs and pitch ups that just keep gaining in amplitude and airspeed. I have not tried holding centralized controls but I can easily see where the plane would start banking due to turbulance and then you enter the death spiral.

Because of this, my new instruments have an artificial horizon (S80).