its been a long time since I flew the ATR, but the alpha will go to 250 with most loads. its just that on shorter routes it doesn't make much sense to go that high due to the time to climb. fuel burn is really about the same anywhere above 180 in it. the ATR handles ice ok, it just does not handle severe ice well. everybody that flys it knows what happened at roselawn and the lessons learned from it. you do not stay in ice with it, you exit asap. if you see ice on the rear side windows you exit now, your in territory you do not want to be in. the book says turn off the A/P and increase speeds by 10 kts. most use more than 10kts.
in the ATR when entering icing conditions you bug icing speeds, the boxes will tell if they crew did that. the CVR will tell the tail of what they saw and how they dealt with it. it could be a case of instantaniouly severe icing that the airframe could just not handle. if it did depart like roselawn did, with aileron reversal, trying to bring the wing up with aileron just made it worse.
the boxes will be an interesting data set.