Decrease in speed with icing
The ATR is very prone to speed reduction during icing. Problem occurs when you have a multiple emergency along with icing - at which time any additional anti icing equipment available is very welcome. It may be worthwhile to test out the laser deicer specified. The other two I am not so sure about
While carrying out an ETOPS I experienced icing at FL 190 with slight but progressive reduction in speed even after applying full anti and de icing measures. I decided to descend, however due to the large distance was unable to contact area control on R/T for a descent. Luckily managed to relay for lower level clearance - which came thru'.
Moral of the story is to choose cruising level with care, preferably take a lower level. Also don't hesitate to add a little fuel to the departure figure even if it restricts the payload.
Hope this helps.