I got the steel version because the teeth (all ten of them) are a little longer than the aluminum version, thus giving a bit more bite when traversing questionable terrain. Besides that, they share some pretty welcoming features which include a rapid sizing adjustment system that utilizes a line of holes fitted by a pin mechanism. (Common to current modular crampon designs)...

With the microspikes, I was able to easily put them both on in less than a minute, and forget about them. Yes you can add spikes to your shoes, but then you are stuck using those shoes for that primary purpose. At least with the microspikes, you can put them on when you need them, and take them off when you don't...