I will be the dissenting opinion here. You donāt need to look to an e-mail forum to decide whether to trust your trainer. Look around at your own community, others in your barn, and the reputation your trainer has locally. My own trainer probably uses draw-reins more than average. Not on every horse, and usually just for short amounts of time. I have heard plenty of comments such as above. I was skeptical when my trainer wanted to put draw-reins on my first/second level horse. I was the one mostly riding the horse, and she was doing training rides once a week. We both rode him in draw reins for a couple months to get through a training block.
But when I look at what this trainer and her students achieve - the scores, the levels, the way of going, soundness, happiness - it is what I want. (BTW, she has trained several of her own horses to GP and trained many amateurs and young pros to FEI, with what I think are very good scores).
I decided that I trusted this trainer more than a bunch of unknowns on the internet, and I am glad that I did. Yes, there are risks with draw reins. Yes, there are horses who learn to head-set and do not develop a topline because of them. But that doesnāt mean that EVERY horse, or even MOST horses will have these problems from using draw reins at times. I have seen several trainers use them quite effectively as a part of a program that includes other things which DO develop true impulsion and connection.
Are there other ways to get the good effects that you might get with draw reins? Probably. Would another trainer do it differently? Quite possible. But trying to force your trainer to do it different from what THEY think is best also has great risks. I would say to look around at your community. Pick the trainer that you trust the most, and then TRUST THEM.