The airplane won't fall out of the sky with ice on it. I flew it 7000 hours over 12 harsh midwest winters (flew N401AM numerous times and knew some of the 4184 crew personally). I carried all kinds of ice and never had a control question. Out of MIA or SJU your risk would be extremely small. Out of DFW, still very small.

That being said, it's an airplane to take seriously in icing conditions. The DHC-8-100/200 uses the same engines as a -42, but is almost as heavy and carries only 37 pax vs. the -42's 46 pax. That's possible by the weight saving aggressiveness of Aerospatiale and also the efficiency of the airfoil they chose. That airfoil is extremely effecient, but extemely untolerable of contamination. It's unpowered controls use tabs and aerodynamics for manipulation and it has an outstanding autopliot (and flight director). Therefore, it can decieve you into a very hazardoues situation if the wing encounters a certain type of icing that is very insideous and degrades the airfoil. The more frequent, usual type of icing that is encountered 95% of the time (that remains on the protected surfaces) is no more problem on the ATR then any other turboprop. Ice that rolls back beyond protected surfaces (freezing rain/drizzle and/or SCDD) is what to exit immeadiately and most importantly to HAND FLY. Control degredation has clues and isn't instantaneous unless............and excellent autopilot hands you a poop sandwich at the last minute.

If you get the ATR, your exposure to that will be very limited, so don't flip (no pun intended), but understand what dark rooms you don't want to explore.