I used the alastics for a while until I "graduated" to the metal ones. My one note if you use the elastic is that if you slid off you horse with your belly to the saddle, the hook on the stirrup can catch on your clothing and rip it. It can also catch under your ribs and puncture you or, if you are short, rip your face.
i like elastic better because if you fall, the band will break and you won't get dragged were as in the metal stirrups you could get dragged
In my opinion alastics are better because, when you fall of, the alastics break and your foot won't get stuck in the stirrup so you won't be dragged.