I am new to fatbiking and I quickly learned that studs are necessary to ride during the winter in my area. Before having studs, I fell constantly. My tires would lose grip and slide like crazy on all the patches of ice. Getting the Dillinger 5s was a big improvement. The bike was able to stay upright better on the patches of ice and there was not any noticible difference in speed or performance. HOWEVER, I have still managed to make these tires slide out when I ride quickly into corners or other aggressive maneuvers. I have just learned that I cannot ride as aggressively as I typically do in the summer on my full-suspension mountain bike. I would still recommend the Dillinger 5s as they seem to be some of the best snowice tires available. But do not expect to gain unlimited grip.
I will ride through any weather condition, but ice always sketched me out. No more, I got studded tires! It was pretty funny when the last ice-storm shut down Portland. I was the only one in my office to make it in and I rode my bike!