I've had to use a Grigri for an emergency rappel and it's not ideal at all. If you're looking for something with a little more friction than an ATC or something you can regulate a little more I would recommend looking at both the Petzl Pirana or the Blue Water Rescue 8. Both are great options for rappelling that give you the option to lock off or ad several different levels of friction. Though with any 8 type device, it will twist your rope up which can be a pain.

you can with single ropes. if you know what you're doing it's super smooth.

I've used it for rappeling down in the gym on self-belay. It works, but if you're set up outdoors, use an ATC. It gets really jerky and that's only going down 40 feet or so.

you can rappel with this, sorta like belaying someone down i guess. Its a bit sketchy but itll do the job

Rappel is a pain with this device. Go old school or get an ATC. It can be very jerky...sp? and I found it to be sketchville.

Unless your experienced in setting up fixed lines for canyoning or caving I would HIGHLY recommend against using this for rappel. There are too many products that cost less than $30 that will be better for rappelling.Only on a single rope or a fixed line. Some people set it up for long rappels on the side of the rope that pulls against the knot, but that's not very safe. Petzl doesn't recommend rappelling with it, and it's just a lot easier to get an ATC and use that.To add to that, I love using this as a rappel device on fixed lines, it is a great and safe option for that.