Miracle Grow compost usually has a lot of fertilizer in it and cacti & succulents only require a very tiny amount so I would advise against using it.

As long as you mix it with equal parts perlite, you should be ok.
Use the smallest stones for grit and make sure they are cleaned of any chemicals and you should be fine.

Nancy

Mixing it with perlite will work, but only for a while. It basically lengthens the time before trouble. Any soil that is based around peat moss is going to have drainage problems, which is detrimental to all plants, and even more so to cacti and succulents. Organic ingredients like peat moss in potting mix will decompose, breaking down into smaller and smaller particles, causing the mix to get more and more dense, which equals worse and worse drainage. Rather than getting into the daily routine of going over this topic, I'll suggest searching the forums for topics about "gritty mix" and the benefits of using a mix with porous, fast draining properties.

Joe