We operate a large number of 145/140/135s and we have never been told of or experianced any such deice related problems,I am not famililar with "powder" de-icing we use Type I,II and IV fluids and the only trouble I had with that is when someone thought it would be a good idea to fill the APU compartment to the brim with said fluid.
As far as flight controls are concerned we have had pitch trim runaways and uncommanded swerving occur in our aircraft and EMB was quick to put procedures in place.
Not wishing to hijack your original post I would like to know if anybody has experianced an oscillation that gets steadily worse until the A/P finally kicks off.I have experianced it on three different occasions twice in the descent and once in cruise.It is apparent the A/P is over compensating towards the end and on the last two occasions simply kicking off the A/P has stopped it immediately.
I have spoken to other pilots who have experianced the same thing and wonder at what point EMB be made aware.
These oscilations cannot be good for the frame over an extended period.
I have over 3000hr in type and not prone to hysterics.