My Merlin with a Rotax UL80 would ice up on me more frequently then I liked. Sometimes it would stumble and recover the whole flight and the next time when pulling power to land only one carb would respond making it very out of balance so would have to do final with full power killing the engine just before the numbers. I found a fellow in BC who made a carb heat kit for the Rotax and I no longer had ice problems. My 0-360 172 has a carb temperature guage and temperature shows in the yellow quite frequently so I check for ice often. Only once I had a stumble on departure when I was around 700 feet AGL it gets your attention. I am always taking off on a grass runway with loose snow on it can this make icing more of a problem?