Art2Ride has gained many more followers over the recent years, which is amazing. Several people have realized the benefits with this way of training their horses. Unfortunately, more followers also mean that more critics are beginning to keep an eye on us.
I've seen pictures comparing a horse that stretches all the way to the ground with a horse that is being ridden in roll kur, under the heading "why go from one evil to another".
In my world one can not force a horse to be in a deep position with the head in front of the vertical. If the horse work in a long, low, forward frame, the reins will have to be very long. The horse will therefor at any time be able to lift its head before the rider can react with the reins. With roll kur, the horse is ridden behind the vertical with a short rein. That is, if it tries to lift its head, it will meet resistance from the reins. I can not see the comparison.