I think autoblocks are significantly easier, especially since you never need to unclip the autoblock from your harness, limiting the chances of you dropping it. The hold is also much looser than a prussic, which is an advantage when used as a rap backup and probably a disadvantage when used for ascending.
I've found it much more friendly as a third hand. I haven't done extensive testing, but I have found it feeds more freely and is much easier to release or mind, while still being happy to bite when you want it to.
A prusik is still my go-to for most other friction knot applications.
I'm curious as to how this (which I know as a "French Prussik") could possibly be jammed. IME, and that of the guides who recommended it to me, this is far less likely to cause jamming problems than a traditional single or double prussik.
For ascending, I believe their recommendation was to use a traditional single prussik for the harness, and this for the leg loop. This is certainly easier to move up an untensioned rope than a traditional prussik, but may also slip slightly more readily, I think.
Personally, I've used it mainly as a backup when abseiling; I can't understand why it's not universally used there (attached to leg-loop and below the abseil device) - you just keep your hand on it and it will allow descent, let go or allow it to move up and you are stopped.
Not true. It is called the autoblock for a reason. You tie it by wrapping it around your rope. To descend, you simply apply a slight amount of downward pressure to the top of the knot. This is the easy to release part. If you remove that pressure, by just moving your hand off the knot, it instantly grabs and stops all downward movement. A Prussik will retain most or all of it's tension, making it difficult to use in ascending or descending. I only use a Prussik in a situation where I want no movement at all for the duration, such as a backup to an anchor.
