I found this thread and it is certainly of great interest to me. I have made, sold and used rope halters for more than 20 years....and find I was agreeing with, then disagreeing with many of the comments. A rope halter is just a piece of tack, in itself completely benign. When it is placed on a horse, it is the lack of experience, skill, technique and a good understanding of applying & releasing pressure in the hands holding the rope that can change the halter into a punishment device.
One thing that is often missunderstood about the knots. On a correctly proportioned and well made rope halter all the knots are located in hollows, grooves and depressions on the horses head therefore do not apply pressure. The 2 areas of a halter that do apply the most pressure, the poll & nasal bone pieces, are constructed with double rope unlike the single rope in all the other individual pieces of a rope halter. This doubles the surface area in contact with the horse so lessens the pressure per sq inch.
I find other problems with rope halters that have not been mentioned...material, quality and sizing. There is a wide range of rope used for halters, some more suited for a dog lead or tying down rubbish in a trailer than equine applications..100% polyester marine double braid is the best rope by far.
The quality varies greatly..always check that both cheek straps & throat pieces are the same length. There is no standard sizing...every maker makes to their own measurements.
I wrote a technical article a few years back that is still valid today..I hope it helps clear up some myths about rope halters.http://www.freewebs.com/lodgeropes/halt ... rticle.htm