I got some time on with a relatively new (slick) piece of 9mm HTP. I backed it up with a new piece of beeline tied into a kleimheist friction hitch, as it was a full sized climb in the middle of a tree (aka tree to hit below me if I slid or the connector pin, which is in R and D, pulled/ pushed out, but it was no problem).
This fed smoothly while rope walking on HTP. 1/2" xtc tended by hand smoothly, but not self advancing when spurring up the spar, with the HH below as back up, a few days ago. I don't think it would self-feed with 1/2", but maybe.
My set-up was good for advancing, and descending, but slid to a stop, or I had to the OAR-h a bit. Wet conditions, slick rope, small diameter.
I will try it on 11.7mm Poison Hyvee next, hopefully today.
I wonder if the rope needs to bend a little more. The middle arm seemed to be doing little 'work'. Maybe the position of the roller needs to be out a few mm, or a larger roller???
I didn't try the different attachment holes. Are they just to adjust the amount of squeeze to release, or do they adjust the friction? Could I get more 'bite' out of a middle or top hole attachement?
Aside from needing a little more friction for small, wet, slick rope, and the developing attachment point becoming more secure, this thing is a winner.
Again, a note, the carabiner clip in hole needs to avoid being able to jam the biner gate into a sideloading situation, a la the ZZ. A slightly bigger clip in hole???