One major difference is the removability of the Microspikes. What do you do at a road crossing? Take 'em off? Click, click, click? With screws/Icespikes, you don't have a choice. And, long stretches on road with IceSpikes sounds annoying and feels weird because of the "platform." From our house, it's about .4 to trails, and that stretch is always annoying and I know that I'm wearing down the spikes.
Before I learned about screwshoes from the TMR forefathers, I used YakTraks. And, I hated the way they altered your foot placement/stride. I wonder how much the "chains" underfoot with the Mircospikes would do the same. They appear "less obtrusive" than the YakTraks.
Meat - The IceSpikes have aerated our floors nicely. We never have to clean up any of Sam's spills!