Regardless of the certification, the icing systems shouldn't be considered capable of allowing one to continue flying in any but the most benign icing conditions instead of getting out. Here's a good example of what can happen when you don't:
"The loss of a TBM 700 turboprop over New Jersey two years ago surprised many pilots. The Pratt & Whitney-powered single-engine turboprop is certificated for flight into known icing (FIKI). For many experienced pilots, all FIKI means is that when the aircraft starts to collect ice, it’s time to move elsewhere. Turbine aircraft don’t usually succumb to a hazard that catches roughly five to eight non-FIKI piston-powered aircraft every winter—and although this accident occurred in some of the highest-traffic-density airspace in the world, surprisingly little warning was relayed to the pilot...
...The TBM entered instrument meteorological conditions while climbing through 12,800 feet and was advised of moderate rime icing from 15,000 feet through 17,000 feet. The controller asked the pilot to advise him if the icing worsened, and the pilot said, “We’ll let you know what happens when we get in there and if we could go straight through, it’s no problem for us.”...
...While at 16,800 feet, the pilot confirmed that, “Light icing has been present for a little while and a higher altitude would be great.” About 15 seconds later, the pilot stated that he was getting a “little rattle” and requested a higher altitude as soon as possible. About 25 seconds after that, the flight was cleared to Flight Level 200, and the pilot acknowledged. One minute later, at 10:04 a.m., the airplane reached a peak altitude of 17,800 feet “before turning sharply to the left and entering a descent.” While descending through 17,400 feet, the pilot’s last radio call was “and N-Seven-Three-One-Charlie-Alpha’s declaring....”
The TBM came down very quickly from altitude, according to several witnesses, losing a wing and taking out part of the empennage before hitting the ground...
...The NTSB determined the probable cause of this accident to be: “The airplane’s encounter with unforecasted severe icing conditions that were characterized by high ice accretion rates and the pilot’s failure to use his command authority to depart the icing conditions in an expeditious manner, which resulted in a loss of airplane control.”